Quite awesome and all, I just thought I'd note that the information regarding Logitech LCD is incorrect for G15 users.
My LCD Manager version is 3.06.109 8th March 2010. No new updates. Also, slightly minor, but the "Internet Updates" button is on the bottom left, rather than right.
Those minor things aside, you have given me a new use for my G15 LCD screen, as it's rarely been given any love! I'll most likely get the Windows gadget too, because my windowed mode is just in line to see any gadgets as well~ :-D
Look for updates to this app that mirror the windows gadget. Also, a poster in the discussion for the windows gadget wanted support for Windows XP, so I might make an option on this one that will display the information in a window that can be moved around the desktop.