Suggested 3rd party apps to complete Qt based "fully featured" desktop.

Note: if is the "QtDesktop" enlisted, the package is part of QtDesktop repository — prebuilt binary packages for openSUSE, Fedora, Mandriva.

• Smplayer — the original fully-featured Qt4/5 frontend for mplayer/mplayer2
• mpv - A media player based on MPlayer and mplayer2. It supports a wide variety of video file formats, audio and video codecs, and subtitle types.
• Vlc — Standalone media player
• QMPlay2 — It can plays all formats and stream supported by ffmpeg and libmodplug. It has integrated Youtube browser.
• Xt7-player — Xt7 is an mplayer gui that aims to be a complete interface to its tons of options coded keeping usability in mind.

• Cantata — Extremely featureful MPD client, with Qt4 and Qt5 interfaces.
• Clementine — modern music player and library organiser inspired by Amarok 1.4.
• Groove — A cross-platform music player based on PyQt5.
• YaRock — Modern Music Player with collection browser based on cover art.
• Tomahawk — The social media player.
• Musique — Music player with a clean and innovative interface.
• Qmmp — Audio-player, the user interface is similar to winamp or xmms.
• Quimup — A client for the Music Player Daemon (MPD) written in C++ and Qt

• qasmixer — sound mixer/volume handler (QtDesktop)
• EKO — EKO is a simple sound editor
• Flacon - Tool to extract individual tracks from one big audio file.
• Qtractor - An audio/MIDI multi-track sequencer application
• Kid3 - Audio files tagger

• Nomacs — image viewer (QtDesktop)
• Photo — A fast, simple, good looking, yet powerful and highly configurable image viewer.
• Qiviewer - A Qt image viewer, designed to be fast and lightweight.

• EasyPaint — Simple image editor under active development
• Pencil — Animation/drawing software

• Converseen — image converter and resizer
• Sir — Simple image resizer in qt4
• Screengrab — Screenshot application (QtDesktop)
• Scribus - A desktop publishing program
• Fotowall — A tool for rendering collages from photos or pictures
• Luminancehdr — graphical user interface application that aims to provide a workflow for HDR imaging
• Posterazor — PosteRazor cuts a raster image into pieces which can be printed and assembled to a poster.
• Trimage — A GUI based lossless image compressor.

• Avidemux-qt — A graphical tool to edit video (QtDesktop)
• ffdiaporama — Creation of videos sequences from images, titles, music
• hybrid-encoder — A very complete gui for video encoding.
• Shotcut - a free, open source, cross-platform video editor
• Feff - Qt frontend for FFmpeg.

• Juffed — text editor (QtDesktop)
• Tea — text editor with an ultimate small sizethat provides you hundreds of functions.
• Qedit — A modern, standalone and multi-purpose text editor.
• Vim-qt — An experimental Qt gui for Vim
• Texmaker — latex editor
• FocusWriter — A simple fullscreen word processor
• Qxmledit — A simple XML editor written in Qt4
• Lyx — An advanced WYSIWYM document processor & LaTeX front-end

• Arora — The original QtWebkit browser, development dead since May 2011
• Opera — Presto-based. Closed source, but very powerful.
• qupzilla — QtWebkit browser, really usable after 1.1.8.
• lightweight2 — Very small browser using Qt libraries

• Trojita - An IMAP email client

• Quassel — Daemon-based IRC client
• Psi — IM app (XMPP only; slow development)
• QutIM — IM app (XMPP + other protocols)
• Kadu — XMPP and Gadu-Gadu IM.
• Licq — Advanced graphical ICQ clone

• Qwit — a client for Twitter
• Qtwitter - Twitter Client

• Andromeda — (QtDesktop)
• Qtfm — Tabbed FM with Bookmarks support
• Newbreeze — Fast and light-weight File Manager (Qt4)
• Hamsimanager — Hamsi Manager is a file manager, renamer, id3 tagger, information changer, ... tool.
• Double Commander — powerful double panel cross platform file manager, written in Object Pascal / Lazarus, which uses couple of toolkits for UI includes Qt

• peazip - Free, Open Source file and archive manager. Supports 7Z, ACE, ARC, CAB, ISO, PAQ, PEA, RAR, TAR, ZIP and many more archive formats.

• qterminal — terminal emulator (maintainer: pvanek, QtDesktop)

• qBittorrent — An advanced P2P bittorrent client.
• transmission-qt — Fast, easy, and free BitTorrent client.
• qtorrent — A Bittorrent Qt GUI

* Silicon Empire —set of tools to Burn, Copy, Backup, Manage your optical discs like CDs, DVDs and Blu-Rays. Dead link as of 2015/09/24

• qpdfview - A tabbed PDF viewer using the poppler library.
• PdfViewer - A simple program for viewing PDF files.

• Clipgrab — A video downloader and converter for YouTube, Veoh, DailyMotion, MyVideo,etc.
• Minitube —A native YouTube client in Qt. Watch YouTube videos without Flash Player.
• Qsopcast - A front-end to p2p TV sopcast
• Rssguard - RSS 0.92/1.0/2.0 & ATOM 1.0 feed reader (QtDesktop)
• Quiterss - A fast and light rss ,feed reader written in C++/Qt4
• weboob - Web Out Of Browsers provides several applications to interact with a lot of websites.

• qftp - A Qt client for FTP file transfer.

• LuckyBackup — Backup & Sync tool
• spideroak - Secure and consolidated free online backup, storage, access, sharing & sync tool for Windows, Mac OS X, and Linux.

• ZNotes —Lightweight application for notes managment with simple interface
• Basqet — A note-taking application similar to Basket
• LoNote — A simple and fast note-taking application using Webkit engine and is written by PyQt.

• copyq -clipboard manager with searchable and editable history.
• TinyMount - is a little GUI tool for mount/unmount devices, using UDisks and Qt.
• keepassx - Cross platform password manager
• qpass - Easy to use password manager with built-in password generator
• ptbatterysystemtray — power management (QtDesktop)
• QBat — A small tool based on Qt4 to display battery stats in system tray
• Qlipper — clipboard manager (maintainer: pvanek, QtDesktop)
• Qps — Process manager. Development is dead.
• qxkb — keyboard layout/language switcher (QtDesktop)
• searchmonkey - A powerful GUI search utility for matching regex patterns
• recoll - Full text search tool based on Xapian backend.
• QGMailNotifier - A GMail notifier.
• Xgrabcolor - A basic color picker
• Top — windowed version of the console top command.
• Taskbar — a transparent taskbar to collect users favorite applications and run them in a simple click.
• Transparency — a set of transparent applications.
• Qx11grab - Qt4 applet for recording x11 windows with ffmpeg.
• kapow - Punch clock to track time spent on projects,

• Calibre — Ebook management application.
• fbreader — An e-book reader for Linux
• coolreader3 — E-Book viewer for comfort reading (epub (non-DRM), fb2, txt, rtf, html, chm, tcr formats supported)

• Acetoneiso2 — An all in one ISO tool
• silicon - Auto image mounter (Iso, Squashfs and ... files ).

• avogadro - An advanced molecular editor
• SpeedCrunch —a fast, high precision and powerful desktop calculator.
• convertall - Unit conversion program
• mendeleydesktop —Academic software for managing and sharing research papers (desktop client).
• klatexformula —KLatexFormula is a program to easily get an image from a LaTeX formula .
• qtoctave — qt frontend for octave.

• goldendict — dictionary
• qstardict — dictionary (QtDesktop)

• LibreCAD — 2D-CAD application

• q4wine — GUI for Wine
• 2mandvd - DVD Authoring Maker In Linux Environment.
• dnetstats - Graphic monitor for the network. Show the network stats and the netmap
• lmms - The Linux MultiMedia Studio.
• musescore - A music score editor written in Qt
• mixxx - Digital DJ mixing software
• vidalia - Controller GUI for Tor
• traverso - Digital Audio Workstation with an innovative User Interface
• scantailor - Interactive post-processing tool for scanned pages
• Synkron - A folder synchronization tool
• coquillo - Edit metadata / tags of various audio formats like MP3, Ogg/Vorbis and FLAC.
• lrcshow-x - A lyrics plugins, supporting Amarok2, Qmmp, and other Linux Players with full dbus interface functions
• qpxtool - Open Source Solution which intends to give you access to all available Quality Checks
• kdiff3 — A file comparator/merge tool
• kchmviewer —A .chm files (MS HTML help file format) viewer .
• cuneiform-qt — Qt4-based GUI for Cuneiform OCR.
• qdvdauthor — 'Q' DVD-Author is a Qt-based DVD authoring suite.
• git-cola — A powerful GUI for Git.
• cdcat — CD/DVD/Media catalog software (Qt based).
• YaNMa — Yet another NetworkManager applet written in PyQt.
• Qcomicbook — A viewer for comic book archives

• Hugor loader - Hugor is a cross-platform port of the Hugo Engine eaning which you can load and play adventure games created with Kent Tessman’s Hugo authoring system.
• Nikki and the robots - futurisctic 2D platform adventure game.
• ColorCode - a free advanced MasterMind clone
• PEG-E - solitare game where you jump over pieces in order to remove them from the board.
• OpenGOO - a free and open port of World of goo.
• GLPeces - create different figures by putting together pieces like squares, triangles, rectangles, and others
• Chessx - operate on your collection of chess games in many ways: browse, edit, add, organize, analyze, etc.
• yabause-qt — A Sega Saturn emulator with Qt interface.
• CuteMupen - Mupen64plus (v2) frontend emulator for N64 roms
• bsnes — Super Nintendo Entertainment System (SNES) emulator focused on accuracy.
• Gottet — A Qt4 tetris game
• Connectagram — A word unscrambling game
• Simsu — A basic Sudoku game

• Webcam application (I suggest[qtcam] http://qt-apps.org/content/show.php/QtCAM?content=170897)
• Font viewer
• wifi/network connection mannager (I suggest qconnman)
• CD/USB ISO burner (like K3b)
• hex editor (For developers), see qhexedit2
• Mail client and/or the whole PIM suite