I've been learning to play the ukulele. I used to play the trumpet in elementary school and junior high, and I can still read music. I've never played a string instrument before.
I started by finding a tuning app for the iPhone. Ukulele Tune is free and does the trick by showing you where your string is tuned relative to the proper G C E A tunings.
I bought a Hilo ukulele from Amazon. I bundled it with a copy of Mel Bay's _Fun with the Ukulele_. It has good chord studies and covers all the chords, it would seem. It also has sheet music that you can sing and play along with, if you were born sometime in the early 20th century. I knew a few of the tunes: "Darling, Clementine," "The Marines Corps Hymn," and "Blue Tailed Fly." But after playing the incredibly dated and racist "Blue Tailed Fly" 1000 times I knew I would drive myself or my wife crazy and had to expand my repertoire.
Fortunately, a friend from my old school who is the music teacher put together a summer ukulele song book and accompanying CD! Now I'm strumming along to the Velvet Underground's "Sunday Morning," playing Dylan's "Blowin' in the Wind," and looking forward to tackling some David Bowie!
It's been great using my mind to learn a completely new skill and to be rewarded with music for my efforts.