Witch!!! It's a free window/application switcher. It's similar to Apple's Application switcher but it lets you use the option-tab key combination to scroll through open apps and windows and then close, minimize, hide them just like you can from within the Application switcher. There's more though you can also unminimize a window from within it without having to go to the dock.
http://www.versiontracker.com/dyn/moreinfo/macosx/25871
http://www.versiontracker.com/dyn/moreinfo/macosx/25871