Not exactly a cover, not exactly a recording by the Dead, are John Oswald's Grayfolded CD's. Here's a review of them by Rob Meador:
John Oswald has been experimenting with a process he calls 'plunderphonics' for some years now. He takes music, and plays with it by transforming the various elements-- slowing things down, speeding them up, layering strange things on top of one another, etc. His several CDs (never for sale and skirting the edge of liable) have been avidly collected by people like Gans, who turned Lesh onto it. In Oswald's own words-- "Plunderphonics is the taking of familiar music and making it strage, or, in another word, new."
Lesh and Gans convinced the rest of the band to let Oswald into the vaults to plunderphonicize the Dead (then they convinced Oswald to do it-- he was reluctant at first). At first, he wanted to work with Dark Star and The Other One, but as the project went on, he realized that Dark Star was a handful, and he concentrated on that. Oswald again: "As I mentioned earlier, plunderphonics usually entails taking what seems to be normal music and making it strange. But with Dark Star, since it often is strange to begin with, the task is inevitably different. Because I've so often heard that the experience of a Dead concert has never been translated to record in a satisfying way, I decided to attempt to make that translation."
He took digital copies of about 51 Dark Stars from 1968 to 1992 (including an acoustic version!), and used them as his material. Two CDs are the result-- one 59 minutes, the other 46 minutes long. In his own words again: "With Dark Star I felt like orchestrating the Dead-- having multiple verions of the band superimposed in vertical layers, so you'd have the Grateful Dead Orchestra for the nebulous sections of the song, which would be interspersed with smaller ensembles." (The above facts and quotes taken from the CD booklet)
The result of all this is stunning. You have multiple Jerry's, sometimes playing at the same time, and sometimes in the same lead. For example, you might hear a line start with what is obviously a 1969 Jerry, and end with an obvious 1989 Jerry. The same with the rest of the band. He really captures the nuances of Dark Stars in general, and there are wondrous, surprising, and very funny things going on. I love Dark Star, and I was leery lest this be awful, but it's not. It really holds the spirit of Dark Star, and is a wonderful testament to the originality and depth of the Dead's music through the years. Highly recommended!