Well, I have been watching and posting on another thread. One thing people are doing is using the Subaru rear differential called the r160 and r180, and even another off the 300zx.
What you do is custom adapt a sprocket to the front of the diff for the input, and then turn your motor 90* inside the engine bay, and extend your sprocket output so that you can run a short chain towards the center of the car where the sprocket now sits on your diff.
You can get the parts to do it from
http://www.belmorerail.com/pages/1/index.htm
They also have a REALLY cheap reverse setup as long as you have a subaru rearend. The subaru rear can be had for $100-200 anywhere, and is limited slip in most cases.
Notice that site belmorerail also has other diff options. One is $1500 and another is like $4k. That one lets you keep your engine mounted trasverse.