Originally Posted by Mr. Shadow

What bike and where/how will you ride it? If you will have a brake or two you'll have a wider selection.
I like Tufos for my clincher rimmed fixies because they can be ridden flat in an emergency and their sealant makes that unlikely. I agree with Gatorskins or similar if you'll do lots of urban riding. Cyclo-cross tires are an option if the frame is wide enough.

I'm pretty brave and have tubular rims on most of my fixies.