Advantages over Skype (VoIP only):
- Free Software
- Doesn't invade your privacy
- Extremely configurable (still straightforward)
- Will work no matter what microsoft decides to do with their servers
- Dramatically less bloated
- Straightforward interface
- Much lower built-in latency
- More advanced permissions system, allowing people to have complete control over their own channels while being banned from others (like IRC)
- You can link channels together and talk between them, despite being in different channels
- You can use push to talk to whisper to individual people while being in different channels
Advantages over teamspeak:
- Automatic dynamic amplitude compression (never mess with someone's volume again)
- Again, extremely configurable
- Servers are ridiculously easy to run and much cheaper generally speaking
Resources for mumble users:
Guide To Everything MumbleSkinsConfiguring The Mumble OverlayAfter mere minutes of work, my mumble looks like this: