Very cool - just a few weeks ago, I spent two weekends (8 hours total) building https://www.delayed-tweets.com. Sinatra on Heroku + Stripe along with a bunch of gems to connect up to Facebook, Twitter and LinkedIn. It's mainly for my personal use right now, but awesome to see others having simliar needs to schedule and cross post social updates.

[edit] The "big" monthly cost for this project for me is primarily the SSL add-on. Everything else amounts to nothing since I have no long running dynos, even for resque.