Developer Color Picker
I've seen this pass around late last week, and finally decided that it wasn't a big issue to get it and see if it's as nice as they say. Certainly, it's more for ObjC developers, and boy do I wish I was one of them, but not today, and maybe not for a while (bad day today). It's nice to see the guys from Panic giving like this.
Anyway, it's here and probably worth getting even if you use it only occasionally.