I’ve transcribed a few Raffi songs for ukulele, mostly for the sake of children I know. These are copied directly from the versions available for download from Raffi’s website except that I’ve omitted the piano part and changed the guitar fretboard hints for use with the ukulele.
In addition to the PDF files, I’m providing the original scores in Lilypond format for people who would like to alter them. Compiling them under Lilypond 2.13.7 or earlier requires downloading predefined-ukulele-fretboards.ly. Note that as of November 2012 Lilypond is not able to correctly autogenerate fretboard diagrams for the ukulele so you’ll have to manually specify fingerings for any chords you want to use which aren’t already listed in that file.