Juancho's is located near the end of Medano Beach, close to the Pueblo Bonito. They have a great, casual little restaurant there where you'll get a great value for your $$. Often times, they'll even refill your drinks or chip/salsa order for free (be really nice and friendly to the waiters).
We found out (the hard way) that Juancho's is the best place to book activities. They are, hands down, the best value for your buck, and they are HONEST. If you're unsatisifed, they will make it right!
You can rent wave-runners, go parasailing, take a snorkeling trip to Santa Maria, etc. Just about any activity that goes on in Cabo can be booked through Juancho's, and you know you won't have any problems/issues like with other vendors in Cabo that may lose your reservations, overbook trips, etc.
Also, you get more bang-for-the-buck with Juancho's. Even though they may charge the same price as everyone else, the service is usually better.
For example, most outfits charge $35/person for a snorkeling trip to Santa Maria. However, we booked our family of five with Juancho's. We got a PRIVATE water taxi, a cooler full of sodas, water and beer, and we left early in the morning before the sun became unbearable. We hand-fed the fish there (bring bread wtih you!) and had a fabulous time. By the time the sun was unbearably hot at Noon and we were ready to leave, that's when the other outfits started showing up. They had 50+ people packed on their boats, and the beach was absolutely overrun by the time those boats unloaded. Had I booked with one of those outfits, I would have been miserable with all of those people, and having to arrive at the hottest time of the day.
When we went parasailing, they sent a photographer out with us. He took some great photos with his digital camera and, when we got back, we were able to view them on a computer and order up some shots. There's no pressure at all... we thought that was a nice addition.
Also, they have the best parasailing boats. They are the ones where you take off from the back of the boat and then when you come in, they reel you in right back down to the landing pad on the boat. The other organizations make you take off from the beach... if you've ever had to do that, it's not a pleasant experience!
Juancho's is very highly recommended for *any* activity in Cabo San Lucas.