Many game companies hire a bulk of their development teams via specialized staffing companies. While it is hard to track down those staffing serviced (there seems to be some secrecy around it all for some reason), if you do some digging on forums, etc. you can find out who different companies primarily use and contact them directly.
Naught Dog, for instance, uses Yoh staffing services http://www.yoh.com/
Many of the staffing companies you do find don’t list the companies for whom they are staffing, but they do list the categories and skill sets these companies are looking for.