I've been building something similar in Erlang/Elixir (OTP's a very good match for an event-driven system which connects a series of inputs to outputs), but never quite managed to get it integrated beyond a few minor inputs/outputs (the fact Erlang is less popular makes finding decent OAuth libraries difficult, for instance). The web interface you've made in particular is impressive; so far my "pipes" are just more scripts.

Well done on this, I'm looking forward to playing with it tonight.