We have a (so-far) working squirrel baffle frotz made from a length of stovepipe hung around the feeder pole. The squirrels can't get a grip on the pipe, and if they climb the pole, they end up inside the pipe, which has a wire mesh screen on top. Would include a picture, but I'm out of town.

As donnad mentioned, the feeder has to be mounted far away from any launch points. Our other feeder, ostensibly squirrel-proof (surrounded by a large mesh heavy wire grid) hangs in the dining room window six feet or so from the porch railing. Even so, every now and then I'll come down in the morning to find a squirrel wrapped around it head-downwards trying to get seeds out, looking for all the world like a big furry sausage. All that does is scare the birds off for a while.

Oh yeah, I tried the red pepper thing. Our squirrels love the stuff.