Are you a fan of Mechwarrior? Don't have a Mechwarrior game?
Fear not! Over at mektek.net, they've released a free version (and perfectly legal) version of Mechwarrior 4 Mercenaries.
Now, some of you might be thinking, "Is this one of those crappy Gundam things where the mechs are impossibly agile?" The simple answer: Nope. Mechwarrior or Battletech is incredibly realistic (gameplay wise anyways, the graphics aren't that impressive) due to elements such as ammunition shortages, overheating, or loosing your leg and then having to limp around the battlefield (20 kph, standing at least 8 meters tall? Yea, you're screwed).