You not going to get very in-depth with anything you find for free online, but if you're willing to spend a little bit of money, Keola Beamer has some online lessons
You might want to think about picking up some of the slack key instruction books that are out too. Ozzie Kotani's book is a good starting point.
Also, like kanaka said, check out taropatch's list...there's also good info floating around in taropatch's forums too
thanks, I just bought Keola Beamer's book. I didn't see your post before I bought it though. When the book arrives I'll see how I like it. If its too complicated for me, I'll buy the one you suggested.
Depending on how much fingerstyle experience you have already, Keola's book is probably going to prove to be too challenging as an introduction to slack key. Ozzie's book (he also has an optional DVD that complements the book) is definitely the way to go.
You might also want to check out Ron Loo's material...he offers CD/book sets that offer printed tab along with spoken audio that walks you through a number of songs as if you were listening to a guitar instructor. His stuff is probably the least-known and most-underrated learning resource for slack key.
Finally, Mark Nelson has a slack key series of 30 video lessons at JamPlay.com. It's excellent material but the problem with JamPlay is that you have to pay a fee ($20/month, $140/year) to access it.
Whichever way you go, definitely stop by the TaroPatch community online and say hi...you'll find it just as friendly and useful as UU.