I just bought some Specialized MTB Comp shoes from work (LBS). I had a pretty deep discount on them, so they're nicer than what I would have bought if I were paying retail, but that said, I think they're great shoes. I'm sure you can check them out on Specialized's website.

As for riding on a fixie with SPD's, I dig it. I've had the same crappy pair of WTB pedals on my ride for three years now (same cleats, too). The bike is my daily commuter and knock-around ride. The pedals have never given me any trouble. That said, I also rock a front brake (so I've never had the problem some describe of accidentally unclippling when trying to stop sharply). The best part of riding fixed is how connected to the bike you are; the SPD's (or any other clipless system for that matter) is only going to make that better.
Cheers.