Hell is your basic, generic, any-where-in-the-world, tourist attraction. It's an area of exposed and weathered volcanic rock formations. They have a couple of shops, a post office, and some of those wood cut-outs that you stand behind and place your head through so someone in your party can snap a picture of you.
Here are a couple of links:
Info on Hell (scroll down a bit): <a href="http://www.caymanvacations.com/indexmenu.htm?general/sightseeing.htm&2">Cayman Vacations</a>
Pics of Hell: <a href="http://externe.net/photos/ll2-grand-cayman-hell">Guylhem's World Photo Gallery: Hell in Grand Cayman</a>
More pics of Hell: <a href="http://home.hiwaay.net/~brogers/Hell-Grand-Cayman/hell-grand-cayman.htm">Hell, Grand Cayman Island</a>
We visited Hell on our first trip to Grand Cayman. We caught an island tour bus not too far from the port and the driver drove us around the island, pointed out various landmarks, and provided a lot of info on the history and current state of the island. It was about $3.50 per person and was actually quite enjoyable. The bus driver stopped at Hell for about 15-20 minutes and we took pictures, bought the obligatory "I've been to Hell" souvenir at the shop, and checked out the rock formations. It was cool but I'm not sure one could spend more than 20 minutes in Hell.