I really want a fixed gear, but I've also been wondering:
Are there any rational or physical advantages to fixed gear (as opposed to SS freewheel)?

I know they're a lot of fun, but there must be more to it. I guess another way I could ask this question is: why do track riders use fixed gear? (again, as opposed to a SS freewheel)

is it about rear wheel control? or efficiency? -- although I can't imagine a fixed gear is THAT much more efficient than a freewheel....
or what?