In fact, you might want to try this with other applications as well.
For instance, if you're working on the Web and there is no need for Flash to be running, it's cobbling up a lot of resources. Okay, I don't know for sure if it's a lot. However, if you've got 5 windows or tabs open, or even 10 to 15 like I typically do, that is sure to add up.
I hate to say this but it could hurt me or as well as other folks who's got ads running off Flash or javascript. But hey, if it helps you work an extra half hour, I'm for it.
Some browsers will allow you to pick and choose what you want running or not. For instance, Firefox 3.5's preference lets you made the choice easily. In Safari, it's even easier. It's all or nothing. Of course, that's no necessarily a good thing either.
I heard this today while I was running and listen to a podcast from Powerpage. In fact, I'm writing this now without Flash or Java enabled. Javascript is running however.
This is merely an extension to what you naturally can do with laptops or netbooks. Dimming your screen, turning off BT, or simply adding more RAM. With battery technology improving, if at all, at a snail's crawl, we do what we can.