I posted here, on the WotC Gamer Classified board, and posted to the my region's Living Greyhawk list when forming my group a few months ago. It took about a month, but I got more replies than places at our table. I started a wait list and we used two from that to replace the ones we lost to turnover.
I found the group I was involved in prior to this one by responding to one of those ads. That was a great group and I only left due to my work schedule change.
We use a questionaire to screen people. works great.