Lotsa brands have a decent fixed/singlespeed bike. I've heard good reviews of IRO, and Tony, who runs it, has a great reputation as an all-around awesome guy. He also hangs out in our forums.

Otherwise, you've got Specialized, Bianchi, Raleigh, and a few other companies, as well as the option of converting a road bike with horizontal dropouts. If you can find an old road bike, I'd recommend IRO's fixed gear wheel set for easy and trouble free conversion. That's what I run, and I like it a lot.