I run Frogs on my fixie, have had them for close to two years now. I absolutely love them - mostly because I ride in Boston traffic and I like that clip out is effortless and can be instantenous. I find them much easier than SPD's, even if the tension is really low. I originally got them because I wanted the float too.

(Oh, and if you ever happen to wipe out around a corner, they slide across pavement really well.)