If you've got a big demolition job to be done, then you should probably consider the stanley line of hydraulic hammers. Actually, even smaller demolition jobs will go a lot quicker with a hydraulic tool. Beats the heck out of using a sledge hammer, that's for sure. They have a number of models to choose from. Everything from hand held hydraulic breakers, to the Cyclone Drop Hammer (check out the video below to see this one in action). The Cyclone falls into the mounted hydraulic category.
Breaking up concrete slabs into easier removal is what these hammers are designed for. While a hand held unit is great for smaller jobs, anything bigger than a 400 square feet needs a wee bit more power. The Cyclone is capable for instance, of doing 1500 feet of street concrete in about 30 minutes. Since it's a tool meant for mounting on loaders, tractors, backhoes, and excavators you can use it in small places and tight spots.
Drill Bit Kit
I've never had a need for this kind of machine, but the inner Hulk in me is trying really hard to find one. It's clobberin time! Seriously though, if you have an old patio that needs breaking up, or maybe even an old pool that your considering demoing, this is the machine to use. I found a pretty cool video of it that's on my website in the link below, where you can see the Stanley Cyclone in action. It's a bit of a sales hype video, but the narrator is kind of funny in his own way.