XFire

Xfire is (besides being a name for the technology ATI uses for Multi-GPU setups) another instant messenger which has the interesting feature of keeping track of many common games. It allows you to see what games and what servers your friends are playing on in addition to providing normal IM and VoIP services. It also tracks game patches and does a few other nifty things. That being said, if you, like me, happen to be a Linux user with friends that seem to use Xfire almost exclusively for instant messaging you may be interested to know that there is a gaim plugin. The plugin, called Gfire can be found here, and integrates Xfire's instant messaging into gaim and displays what your friend is playing and on what server if you hover your mouse over their name. If you just don't like the Xfire client, there is also a build for the Windows version of gaim.

Just what the world needs, another IM protocol, but the gaim plugin is handy if you need it. Get it here.