On an interview on this site, Jerry Garcia claims his reason for playing with the Jerry Garcia Band wasn't so much to make his own personal music as it was for him to express what he likes about music as a whole, giving him a chance to play music he's a fan of. It's a healthy outlet to be sure and, along with the other members' side projects, probably one of the main reasons for the Grateful Dead's longevity.
This playlist features one-time members of the Grateful Dead playing with various friends, either in full-fledged side projects, as guests sitting in for a jam, or in their other careers before they became members of the Dead. While the genres and recording quality contained here vary greatly, there is an underlying sense of looseness and fun in all of these songs, showing that those that were chosen for playing in the band did have something in common...intangible as it may have been.