I really like what you are doing with the ukuele lesssons, I especially like the fingerpicking lessons as I fingerpicking seems a lot more natural for me.
I have a few suggestions for songs and lessons that you could consider:
Down by the Riverside
Jesus on the Mainline
They're Red Hot
I'm a Bad, Bad Man - Ukulele Ike
Dying Crapshooter Blues
Any sort of country blues or ragtime
Lesson on how to take something from record and convert it to uke
Keep up the good work.
Sporting Life Blues and Rye Whiskey would also be good..