Windows: Shotty is a lightweight and portable screen capture tool that captures screenshots in Windows Vista and 7 while preserving the transparency of Aero-Glass effects.
If all you need is to capture windows with the transparency intact, Shotty does a great job. On top of eye-candy preserving capture, however, it also includes a built-in editor for easy highlighting and annotation. Shotty has support for easy screenshot sharing via quick uploads to popular image-sharing services like ImageShack and TwitPic.
It comes packaged in an installer, but you can opt to install it as a system or portable application. Shotty is freeware, Windows only. Have a favourite screen capture tool that preserves all the eye candy of modern operating systems? Let's hear about it in the comments.