I'd suggest checking out 48hourslogo.com. You put up a reward for the designer of your logo (minimum $99, I offered $129 for mine) and you get tons of graphic designers creating concepts for you. I ran my contest for a week and got around 50 entries. Then, you pick three designers that you liked, and ask them to revise as you see fit. After another week of revisions, you pick a winner. It's a pretty awesome service. This was the contest that I just ran.