You know, I used to do the exact same thing. I wore hanes shirts or a plain ol' tee. But I purchased a jersey from a local Swap Meet a week or two ago and it's just so darn comfortable while biking longer distances. At $10-15 a pop shipped I really can't complain at all. I know jerseys can get pretty pricey, but I think it's worth having a few for those long trips/hot days! I've never worn a jersey in the winter, but I'm looking forward to it.

@ Scooper: That sounds like an amazing ride Scooper! I want to do something similar one day.