I've been enjoying the quirky animated music videos for the songs from Here Comes Science, They Might be Giants' album of science songs for kids. Eric Siegel, Director and Chief Content Officer of the New York Hall of Science, advised TMBG on the content.
Here are a few about biology:
You can download the lyrics and guitar tabs for the songs on "Here Comes Science" from this might be a wiki. Perfect for your next sing-along!