Download : http://www.ntwind.com/software/winsnap.html

WinSnap
is a clean, fast, simple and user-friendly utility for taking and editing screenshots. It can easily capture windows of non-rectangular form with customized and transparent backgrounds, including Aero Glass on Windows 7 and Vista. WinSnap adds eye-candy drop shadows, reflections, rotations, watermarks and other effects on the fly. It supports a variety of image formats and provides advanced auto-save features.

WinSnap Settings - Shadows like in Windows Vista