Bernadette Teaches Music YouTube Channel This YouTube channel has lots of step-by-step instructional videos for many strumming techniques and songs
Little Kids Rock-Ukulele Little Kids Rock is a website with many instructional videos as well as song sheets for current radio pop songs
Dylan Layne YouTube Dylan Layne's YouTube channel teaches lots of Contemporary Christian hits.
Acoustic Bridge This website has a huge list of 4-chord songs as well as tutorial videos for each. It also has a nice buyer's guide to help you decide which instrument to purchase.