I'm using my own revision of 3.5. It contains a lot of proprietary stuff, so I can't really share it, but it goes further than the Pathfinder revision when it comes to streamlining, embraces several 4E concepts that I found intriguing, and also tries to flatten the power curve (without making all levels play the same).
Working on it is a mamoth task, especially since I can't really devote more than 1-2 hours per day to it, but I'm using the revised rules in two ongoing campaigns and players seem to have embraced the changes.