This one takes a little muscular strength and tenacity, but it can provide surprisingly enjoyable results. In particular, I find that this technique both extends orgasm length and significantly increases pre-orgasm pleasure.

Begin by lying flat on your back. Start to masturbate. When you reach a point where you're completely aroused but still a ways from orgasm, lift your legs several inches to a foot into the air. Actually, a lot of times I find it easier to lift my head and chest a few inches as well, so that I'm balanced entirely on my butt. What I find is that the pleasure of masturbating usually increases immediately when I go up into that position. If I'm lucky, sometimes I'll hit that wonderful point where I feel like I'm on the verge of an orgasm, but it will last for anywhere up to a minute before I actually come.

The down side to this trick is it can be a very difficult position to hold for long. If you lift up too early into the masturbation session, you might not be able to hold it all the way to orgasm. This technique is obviously a lot easier for guys who are in good shape, but on the plus side it gets less difficult with practice.