Christians have always used (and abused) new types of media for evangelism. Beyond such things as Chat Room Ministries and Online Evangelism Kits are teams that witness in online games. This month, CGW/1up.com has an article called God Mode, in which they interview the guys at Christian Gamers Online, whose describe themselves this way:
A group of Christians that use online gaming as a ministry. We play with dignity, respect and sportsmanship in the Following Games: Ghost Recon, GR2, Halo, Halo2, AA, BF1942, BF2 and many others. We use a program called Team Speak to talk, plan and strategize while we are playing.
The interview is not the greatest, but it definitely is interesting. As you may or may not know, there are quite a few Christian gaming organizations. For more info, check out the following: