I'm actually surprised there are so many here who haven't been overclocking. I figured I'd be the odd one out. With my last PC I did a lot of OCing, but ever since I got my 2500K about a year ago I haven't bothered. I really don't do much of anything that stresses out my PC so I've just left everything stock. I'm just not the gamer I once was and the games I do play are games that I can play with my friends, who have older laptops.
When you think about it, overclocking isn't really free performance. The money spent on fans and heatsinks does add up. I think of it more as a cheap upgrade when you hit the point you can't max something out. A heatsink is a lot cheaper than a new CPU.
I used to be proud to be an audiophile, but when you go from "isn't $50 a bit much for a headphone" to "cool, only a few hundred" and you start selling off parts of your PC to get your next fix... oh well. It's still cheaper than being a car guy.