Another panorama
Originally uploaded by j_wijnands.

Or Image Composite Editor as they prefer to call it. It's free and can be found here: http://research.microsoft.com/en-us/um/redmond/groups/ivm/ICE/

I downloaded when I, once again, got an error message from Photoshop's photo stitcher function.

This is way better than photoshops. Handles a lot of formats, autodetects what's the best solution is and stitches. Two drawbacks
1. It's extremely slow in VMWare
2. It tends to default to saving a very small version of your pano.

Besides that I really like it.I just use it to stich horizontal panoramas and export to plain old jpg but this tool can handle loads of things such as HD view and Silverlight deep zoom