There are a couple good ones already on the market, and I'm awaiting the release of Omega Sports "Ultima". Numerous setbacks though with it's release, which is frustrating.
Body Octane by MAN is a great stim-free pre-workout supplement. If you are looking for something with stimulants however, just not caffeine, there may be a few out there. Best bet though, if you want this route, would likely be to contruct your own coctail.