Some of the open source projects I've been involved in:

Adhearsion

https://github.com/adhearsion
Adhearsion is a full-featured framework to simplify the development of applications with voice communications.

Cancancan

https://github.com/CanCanCommunity/cancancan
CanCanCan is an authorization library for Ruby on Rails which restricts what resources a given user is allowed to access. Originally built by Ryan Bates and continued by myself and the CanCanCommunity.