Well, I sort of have a strange vendetta against derailleurs, and I am perfectly fine with a three speed. But a single speed tends to be cheaper, Also, because pretty much all children's bikes are single speed bikes, and that I remember that the hills really aren't that bad, I figure a one speed should be adequate for me (yup, I'll never forget my own childhood). I only need to get back home from my summer classes which is five miles at most, the occasional get from point A to B, and most universities probably won't be so mountainous that a single speed can't manage.

Nonetheless, what bike do you use? And what is "Fixed gear" and how is it done?