What are the best panoramic stitching programs?

I was thinking this summer that I'd like to get some larger pano style prints. Like 10x30 or 15x45. The planets seem to have to align for me to get a shot that really works that big with my 20D. I'll be getting a 5D shortly, just not sure when exactly. So I was wondering if you guys could point me in the right direction on software and the best way to go about it.

Thanks!

For a PC, try the free program from autostitch.net. Its easy to use and gets the job done where Photoshop's Photomerge can't quite cut it.

Many of my panoramas were done with it: http://www.pbase.com/csully/panos

Jeremy, you're getting a 5D? You lucky dog! You're not going to go all snobbish on me now, are you?

I'm set to buy the 1Ds2 but now rumor is a 22 MP in the Fall, so... wait I will...

I had a Canon rep. directly contradict that last week Ned. He said "no chance of a new 1-series DSLR this year". However, Canon may just not be willing to confirm such rumors.

hmmmm...22MP thats sounds tasty! Not sure I could wait....or really need to?

Also try Panorama Factory

I've use autostitch with some pretty awful auto-exposure variations and it blended them better than Photoshop could. Point the program at a folder of pano shots and it does all the work. Just be sure you have enough overlap so it can detect where to line up the images. Also, shoot vertically for really high detailed panos.