CD keygen's

Where do people go to get keygens. my friend just got Half life 2 and he said if I can find a CD key for it I can install it on my comp to, so where do you guys go i found a site called http://www.crackfound.com/ and they have a whole bunch of cd key stuff but I have no clue what to look for.

let me give you a little hint, kiddo

antivirus software isn't going to detect a random .exe that joe schmoe wrote to post on his spam webpage that puts CP all over your desktop unless MAD other heads have been downloading it