Have one of those T-shirts. Its from the LIFE IS GOOD company which is a neat story in itself if you want to research it.
http://en.wikipedia.org/wiki/Life_is_Good
the shirt says "not all who wander are lost". A slight change from the exact quote as Folwren indicated. I thought it was neat to see a LOTR quote on a shirt with no other reference to it. The people who ran the store had no idea.