There is a great thread on Mudcat - "Songs for/about Phil Ochs". I think we should have a similar thread for Woody too. There are a lot of Woody Guthrie tribute songs written by great songwriters. A few I can think of right now:

Bob Dylan - Song to Woody
Bob Dylan - Last Thoughts on Woody Guthrie (poem)
Phil Ochs - Bound for Glory
Tom Paxton - They Couldn't Take the Music
Guy Clark - Walkin' Man