There's also some thinking that I could probably just re-use Leaflet for this. The real point is having zoomable images, so people can focus on details of the plug image to figure out its location, while not having to load a giant image on mobile.

In fact, here's a crazy idea: could we have the client split their image upload into tiles? That would be awesome, and make the upload a lot less flaky. (Probably too complex to do, though. What would we do when only half the tiles for a plug have been loaded?)

Are the JS file / image handling facilities for that even exposed in Chrome for Mobile / Safari / PhoneGap? (I've never heard of a resumable upload facility in HTML5.)

And who does image manipulation (even if it's just cropping) in the browser? Besides, this is oriented toward mobile users, with mobile power on a mobile connection.

The point that was made at tonight's JS meetup is that OpenSeaDragon allows smooth zooming to any size, while Leaflet snaps to zoom levels.

Although it looks like Leaflet supports fractional zoom too as of a little less than a month ago.

https://github.com/openzoom/node-deepzoomtools has some stuff for converting images to tiles, although CoffeeScript (ugh) and it's oriented around Seadragon's whole XML format thing. So, something to pull from, if not to use as a whole.