I think perfect candidates for re-editing are the "Kill Bill" films. Think of all the possibilities that one could do.
As for the Matrix sequels, I always thought that they were really about one 2 1/2 hour movie split into two 2-hour films. Reloaded especially. There's all sorts of crap that could be cut out of it. I don't understand why they actually want to add footage. At some point I'd like to edit both Reloaded and Revolutions together into one 150-165 minute film.
I also plan on editing the dvd release of the "Blues Brothers" back to the theatrical version.