You know, I'm about to do something similar myself... a directory for freelancers. I think the only real problem is that there are so many of these types of sites out there. You did say you were going to specialize a little, but I'd look at specializing a LOT. Also, make sure that your prices aren't so low that you're not making any money, but not so high that no one will pay them. Most people aren't willing to pay for advertising unless there are stats for traffic and such. Have you sat down and looked at the different ways to build up that traffic before hand? I know that we're going to offer free advertising for the first 3 months. In order to hopefully build trafffic to the site. Also make sure you get a good domain name if you can. I am in no way an expert in these types of sites, but I'm learning with you....