Notice no one ever covers a Bob Weir song? Ever ask yourself why?
In The Grateful Dead Movie, Weir's lyricist, John Barlow, says something to the effect of "no matter what, we'll never write anything half as good as Garcia and Hunter. They ARE the Dead".
(Weir, sitting near by, looks chagrined...)
The Decemberists do "Row Jimmy" (Weird choice!)
Jeff Tweedy of Wilco does "Ripple"
Vetiver does "Don't Ease Me In"
Built To Spill does, um, "Ripple"
Cracker does "Loser"
Ryan Adams does "Wharf Rat"
Not a fan of this guy, but Billy Corgan recently did "Morning Dew" in the style of the Dead (as opposed to the Tim Rose/Jeff Beck etc arrangement)
and lastly, this all star band doing "Tennessee Jed"