Rest ($4.99, Mac & Windows)
A break reminder app with (optional) exercise suggestions. Originally made exclusively for the Mac, it's also on Windows now, with a helper app available for iOS and soon Android.
Made the first version almost 3 years ago, and been slowly (but surely) adding features/improving it since, though very low-key. A university in the US as well as some companies are using it, so that's pretty cool.
This is all very useful info. I've been incorporating some similar habits (eg for break timers I use the Rest App on my Mac to lock my screen and display hand/wrist/shoulder exercises every 20 minutes) and it's nice to know how others work as well. I never considered double trackballs and I actually just got a Ploopy Nano so this is perfect timing to try that out. And baoding balls sound like and excellent addition to my desk fidget collection. Thanks for sharing!