The title pretty much says it all on this one. If you activate Exposé by hitting F9, then all of your windows show up on the screen. From there you can click on the window you want, or you can hit Tab, and tab through them one by one. This is really helpful if you have a lot open and need to get a better look at it to make sure you’re selecting the correct window that you were actually looking for.

Now keep in mind, this doesn’t work within just one program, so you if you hit F10 to open the windows in something like Photoshop, when you hit the Tab button it will begin cycling through every window open on your system.