I once had this happen to my '98 Silverado. Did all the above suggestions and ended up riping up the filter until it was unrecognizeable. I was at my wit's end.
So...I swallowed my pride and called up my dad. Who then came over with a chisel and hammer. Althought I didn't think it would work, Dad has shown me many different ways of doing things in the past, so I let him at it. He cut away the filter until he could get the chisel wedged into the top of it. Outer top that is. He then started tapping it with a hammer and guess what...it started to move, then a little more, then a little more, then it let loose and that was it. Dad got a handshake and a beer and I learned how to get off an extremely stubborn oil filter.
Jamie is right...put oil around the seal and hand tighten only. I forgot to put some oil on that filter and that was the result. Btw...when you get it off, make sure the seal is not stuck on the car.