While I really enjoy MMORPGs, I also enjoy racing. Project Torque on Aeria Games combines racing with MMO to create a MMORG (Massively Multiplayer Online Racing Game). You choose a sex, one of four starting cars, and you're off. If you enjoyed Gran Turismo 3 you'll love Project Torque. You can buy new cars, upgrade and customize your current one, buy "flag girls", and many other items. The large volume of customization makes the game quite fine. Besides street racing, drifting, offroad, and more plays a role in your ability to drive. Movement with the arrow keys keeps it simple yet fun.
This is a funny Aeria commercial if you're interested, reminds me of Office Space.