Windows ALT-TAB - Mac Equivalent?

I'm still on the curb trying to decide when the best time to make the switch to a Mac is, although the new 17" PB just might be the kick in the pants I need - but I digress...

In Windows, there is a handy-dandy feature that allows you to quickly switch from one application to another. You hold ALT and tap the TAB key to surf around all your open windows.

I do a lot of webwork and am constantly changing from Flash to a scripting window to a browser, et cetera, and I've become quite a slave to the feature.

Is there a Mac equivalent to this function?

Good God, you people are fast! Thanks for the info - one less indecision point, not that I was going to make my switch decision ride on the existence of a single feature on an otherwise perpetually annoying platform.

Thanks again!