*Go clipless
*Speed up on the flat before the hill and build as much momentum into the beginning of the incline as possible. It's one of the best parts about fixies-- you carry you inertia further.
*Play mental games: imagine your headube is attached to a reeeeeeaaaly long bungee cord attached to some landmark halfway up the hill (i.e. a mailbox, lampost,tree, etc.) and that it's pulling you slowly up to that point. Once you reach that point "reset" the bungee to the top of the hill.
If it's cold and rainy and I'm on my way home, I try to imagine a warm bed and food and wine and stuff on the the other side. Silly, I know, but what else do you have to thing about when grinding up a hill?