VIRTUAL DUB can be used to rotate a .AVI file. It's free, documented and does this so I can't offer anymore than http://www.google.com to find it.
Bob
Real newbie question I'm afraid. I have created an .avi with my digital camera turned 90 degrees so the video is portrait. How can I turn it so that it doesn't play back in Windows Media Player on its side?
Thanks for any assistance.

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic