A colleague of mine is working on a custom application which makes extensive use of SharePoint lists to store data. He has written a webpart that rolls-up the XML data from various lists, transforms it with XSL, and renders it in a way-cool tabbed control. While putting this together, he found this link on Using Data from Sharepoint 2003 Lists. Very cool and a big thanks to Paul Ballard for his post.
Perhaps if we needle him enough, Scot will be nice enough to post his nifty code and show us how it's done. Or, he could just get a blog and start sharing his wizardry with the rest of the world, eh???