Steve Martin has always facinated me. Several things have pointed me his direction. There is a point in the expired TV series "Freaks and Geeks" where Sam (a main character) is listening and laughing to one of Steve's comedy albums. After that I searched out his comedy albums on vinyl. A while back I saw a documentary about him and his career. Also, my stepmom told me to check out his autobiography that came out in 07' as well.
If you have the slightest interest in him you should check out 'Born Standing Up'. It's very interesting and entertaining. There's a story in there about an interaction that Steve had with Elvis that is priceless.
As far as Steve's banjo playing; He's no Béla Fleck, but he ain't bad. I've seen him play a few times on 'The Tonight Show' with bluegrass 'A-list' players like Earl Scruggs and Tony Trischka.
Steve, Tony, and Béla on the tonight show
His compositions are pretty good, as well. He's one of those people who have oozing talent but think they have none.