If you're one of the many talented mappers out there Tripwire has a contest just for you: they're looking for some amazing submissions for Wave 1 of their Killing Floor
mapping contest. If creating astounding maps isn't enough incentive, how about the chance to win $5,000 as well as some Nvidia graphics cards and Logitech goods? Now those are some good prizes.
If you're interested the deadline for entries is July 31st at noon (so you best hurry up); for more info on how and where to apply, and for info on Wave 2 (where the prize doubles to $10,000) check out the contest's website