I recently was in contact with Mark Miller at endusersharepoint.com. He's putting together some great material on content types, which is available through a free weekly newsletter. I highly recommend subscribing; here's an installment re: site columns and content types, which Mark gave me permission to share with my blog audience.
There are not many end-user-focused sites out there for SharePoint; this one is a really valuable resource with a down-to-earth point of view. Check out, for example, "How come I keep seeing that *^!#ing authentication screen?"
