Not asking you to write a business book or anything, but can you give an example of the sort of thing you're thinking of? (Is callinwith.us an example?) I looked at Twilio because I thought it sounded really cool, but in the end I couldn't think of many Twilio applications that 1) have a clear revenue model, and 2) aren't already features of Goldmine or similar that anyone who wants it would already have.