I think this version of this quintessential old-time piece is a great intro to tab reading (without even worrying about the clawhammer stuff) - it`s also a perfect intro to the clawhammer technique ... but now I think I'm going to have to get me one of them banjoleles!
The idea here is that the four tabs are a progression from picking just the simple melody, to adding in pulls, hammers and even thumb drops. It also has the simple chords so the less intrepid can join in.
Check out http://www.ezfolk.com/uke/Tutorials/Clawhammer/clawhammer.html for an intro to clawhammer on the uke and for other great examples by this guy.
A video for this song: