When I was in PVR (see my "if you are in puerto vallarta..." post)
I went on a jeep safari through Vallarta Adventures. Our tour guide (who is in charge of the jeep safari expedition) mentioned he was recently in Cabo setting up Cabo Adventures there.

He said their Jeep Safair/Desert Safari excursion was awesome. I know I had fun on my excursion in PV. Also, many people have said the canopy tour was awesome... though this is the one in PV, Cabo also has their own.

Its a great company if you are looking for adventure. If you do check it out, let me know how it went!