One of our favorite sites for iPad info, PadGadget.com gave a nice quick write on aviation apps for the iPad. If you are a GA pilot ForeFlight is pretty amazing. You can try it for free for 30 days. So check this link out and we will ad additional ones as we come across them. The iPad is an amazing device for this type of stuff. RAM makes mounts for the cockpit and I can really see this taking off, so to speak.
http://www.padgadget.com/2010/07/30/ipad-best-co-pilot-around/
Jeppesen Site: http://www.jeppesen.com/microsites/jeppesen-mobile-tc
ForeFlight: http://www.foreflight.com/mobileiPad.php