Lynda.com - a couple of good tutorials. Try Jan Kabil. Chris Orwig is a little long winded, but ultimately goes into more depth.
I have the Scott Kelby Lightroom 3 book, and it is very good. Simple, how to get the job done, with lots of little tips and insight. Not a lot of theory and background on how the database works, etc, but very practical usable advice to get you going.
Adobe TV has a really good video on how the database is structured.