StarryNight
Sample beautiful Windows application with animation in WS_EX_LAYERED | WS_EX_TRANSPARENT window.
This sample demonstrates a lot of techniques: drawing with animation in WS_EX_LAYERED | WS_EX_TRANSPARENT window (on top of all other Windows applications), using mouse hooks, getting display scale etc. Here is the result:
You can find bigger open source project that uses these techniques here: http://pxper.com/.