My friend Roger turned me on to a website on which a Virginia musician, Patrick Costello, and his dad teach a folk song a day. It's banjo and guitar, and lots of advice on playing in a jam situation. Even if you aren't learning folk music, it's an extraordinarily good site for watching a gifted teacher in action.
This is the sort of Internet content that, had it been around when I was a teenager, would have changed my life.
Check out Tangier Sound. And, if you're in the Chesapeake Bay area, the Costellos are hosting a weekend musicians' retreat in Crisfield, Maryland, in late August.