If you're into productivity, you may have been left wanting a little with Vista's new task switcher. The OSX folks have had Exposé for ages, and there are alternatives for XP users. However, Vista's new Desktop Window Manager is paying off - several alternative task switchers have shown up. Here's the first one I've found that does the job well. Simply called "Switcher", it is available here.

When you simply press either a predefined hotkey, or mouse over a hot corner of the screen, it zooms out to show tiled versions of all your applications. You then click on the window you want to switch to, and it zooms back out to the selected application.