OK, I've been looking for something like this. Unfortunately, it's not quite there for my taste. I should have known that when I saw John Welch slipping all over his self-serving drool. What a 'tard. For now, I'll forgive the oversight :-)

On the good side, there is a pref to not have it appear in the menu bar. Thank you. Also good, a key-stroke to bring it to the front. This is where it falls short IMO. I frankly want this to be able to supplant Apple's command-tab, which I personally never use. But that is being trapped by the OS, so Apple is unlikely to make it easy for any outside programmer to write their own trap for that keystroke. Lacking that , I'd like to see a defined keystroke be able to cycle through all the locations (a la command-tab). Do that and you have a winner (and a license payment from me).