I had the best comeback in awhile today. I was playing Neutral Assault on Avalanche, and the other team was quickly able to detonate two bombs. I'm not sure what happened, but four people on my team quit, leaving only me and two others remaining. So we played defense for about a minute or two, successfully preventing the opposing team from getting another detonation and winning the game.
For some reason, three people on their team quit (I think they were fooling around), leaving it 4 to 3. We managed to tie it up and win the game in the end.
http://www.bungie.net/Stats/GameStatsHalo3.aspx?gameid=964053765&player=dax01
Hadn't had a game like that in awhile.