I read somewhere that swimming is the most hunger-producing aerobic exercize among the more common aerobic exercizes like running, biking, or dance/step. I think there were some physiological reasons for it including having to maintain body temperture in the high 90's while you body is emmersed in 70 (or so) degree water. As several folks have noted, it is usually a good idea to plan a high protein snack after any serious workout to help build and rebuild the muscle you exhausted during your exercize. So if you can arrange your diet to include about 150 cals post exercize you will be stronger AND well fed.
That being said, I have never been hungerier in my life than when I was training for a marathon - not that I really needed the calories, like many I maintained weight, there was just something out of wack in my diet/running plan.