Ever wonder how your friend got into that sweet game beta test? Sites like this help you find them. I have beta tested games in the past (like AO, Planetside, SWG, and others.) Was quite fun and that many people trying to find bugs in a game (not all do, but hopefully enough do) help make a game better for release. Google for beta games, follow msg board, etc. Those little tricks won’t for sure get you into the beta test for a cool game, but will make it more likely that you will find one at the right time.
Plus the perk usually is at the very least getting to try the game out for free to see if its worth it. Not very altruistic true, but that is how a few game beta testers see it.
Give it a shot though. Favorite beta test anyone has been in? (Personally Planetside was awesome in beta.)