I'm looking for a hat pattern for circular needles. I don't own any straight needles so I'm having some difficulty locating a pattern that's right for me. I have a whole bunch of circular needles so any size is fine. The yarn that I'm using is a chunky acrylic, so it requires bigger needles (9 and up). Any patterns?

There are a slew of patterns here:
http://www.knittingpatterncentral.com/directory/hats.php
http://www.dailyknitter.com/patternsdetail.php?type=HA
http://knittingonthenet.com/hats.htm

Most hats are circular, so you just need to find one in the right guage.