I think I found a good one! I'm at work right now so I can't download it and test it, but it's the DVD Profile Mobile by Invelos Software (
http://www.invelos.com/dvdpromobile/Info.aspx)
It looks like there is a Windows desktop application as well. Put your DVDs in the desktop app and it'll sync with the PPC app. You can make changes to either DB and sync the changes back and forth.
And it doesn't have the butt-ugly interface that most PPC DVD apps seem to have...
I'll try this out when I get home.