I am using Sidekick with the Palladium Rifts & Robotech\Macross pen & paper RPG system, & their attribute rolls are a little different than most:

For most human characters, the basic rolls for each attribute are 3d6, with any subtotal above 16 getting an additional 1d6. (Some character types get 4d6, & it's even possible to get additional bonus dice with a few choices.) The usual exploding dice rolls will just keep rolling if sixes are rolled, so 3d6! isn't helpful in this case, & the 3d6>=16 still requires rolling again for the bonus so that's not much better than just checking for the bonus manually...

I think it would be really helpful to have a target beyond which an extraordinary stat gets additional rolls:

/r 3d6n16b1
would return the total of 3d6 if below 16;
if 16 or higher is rolled, one (b=1) additional d6 would be applied to the total, so:

1d6=6 + 1d6=6 + 1d6=3 returns 15; but
1d6=6 + 1d6=6 + 1d6=4 (subtotal 16) + 1d6=6 returns 22!

In addition, /r3d6n16b1! could be useful here, so that:
1d6=6 + 1d6=6 + 1d6=4 (16) + 1d6=6 + 1d6=6 + 1d6=2 returns 30!

I know I personally would find this feature enormously useful, as it would expedite the many rolls needed when creating a Rifts, Robotech, or Macross character.

As a side benefit, the code necessary to support the format #d#n# could provide some basis for future roll modifiers to check for success quality (anything n# or above being a success). This could be a real boon if someone wants to implement quality rolls, such as 1d100+10n24q33, where anything below 24 would be a failure, 24 a poor quality success, 57 a good quality, 90 & above are exceptional quality. I don't expressly need graded quality rolls though, so let's call that a stretch goal. ;)

Please let me know what you think?