Whereby (formerly appear.in) - Collaborate from anywhere - video meetings with no downloads
Linkello - Video calls simplified, no installation required.
Brie.fi/ng - Start secure group video chat
jTorchat - jTorchat stands for Java Torchat, and is a complete rewrite of the popular p2p IM messenger Torchat
MeetSpace - Video conferencing for teams that doesn't suck
Signal - Fast, simple & secure messaging. Privacy that fits in your pocket.