Thanks for sharing! Here are my comments, mostly critiques but please note I really think you have a great start here.

Nice clean interface, reasonably quick to use.

Doesn't work with 1password.

HTTPS isn't the default, and when requested gives a cert failure (representing *.onmodulus.net)

Email notification should be opt-in? Also should have a toggle for product notifications.

When I click on someone like http://chapp.is/people/hayk/activity the profile link takes me to my profile instead of theirs.

All in all, I'm looking forward to watching this service grow! (p.s. I suggest looking into PostgreSQL 9.3 as a backup plan to Mongo)