@Merlin: I agree that Theme Porter has a nice selection of ported templates. Well, one of my open source templates have been featured and ported by them, so I'm a bit biased.
If you already have a design that's been coded and all, and you just want to port it to WordPress, and you've got 10 bucks to spare, you may want to give
http://www.themespress.com/ a try. You get your theme within a few minutes. I know the guy, he's really professional. (And no, I don't get any commissions to suggest his site
)