CrossGL SnapDraw, formerly called CrossGL Alpha Screenshot, is a screen capture utility that can see the Windows Aero interface natively. That means that if you capture a window with a rounded corner, the utility won't grab the pixels behind it as if it were a square window. This ability makes SnapDraw ($30, 30-day free trial with some feature limitations) very useful for technically accurate screenshots.
Another of one of SnapDraw's main features is the ability to place magnifying glasses directly on the captured image. These objects magnify a specific portion of the screenshot in a circle, and you can then use SnapDraw to tag that magnification. This is useful if you need to point out specific features of a captured image.
To use SnapDraw, you first need to set up a Capture Key in the appropriately named dropdown menu. Click on Activate to make it Shift+PrintScreen. Other screen capture utilities, such as X, define keys automatically on startup, so it seems odd that this extra step is necessary for the app to function correctly.
SnapDraw competitor (and reviewer favorite) ZScreen allows you to automatically upload screen captures to an image hosting service like ImageShack. SnapDraw can't do that--but it can capture to a file or upload to an FTP site. ZScreen can't do the magnifying and tagging thing, though.
Another thing that SnapDraw can't do is capture hi-res game screenshots, something that ZScreen can do. I attempted to capture a screenshot from Dragon Age: Origins, and it came out to a black screen. SnapDraw's origins in the OpenGL standard--and the fact that most games use Microsoft's Direct3D instead--is a likely culprit.
SnapDraw can make cool reflections, distortions and image manipulations to your screenshot--wonderful for advertisers creating back-of-the-box pieces--but there's a critical missing feature. There's no Undo command, either in a menu dropdown or via the standard Control Z. For those doing a lot of image manipulation, at least one level of undo is required, and several levels are preferable.
Considering competitor ZScreen doesn't have any image manipulation tools at all, CrossGL SnapDraw has several advantages over it. However, the lack of an undo, the inability to take high-res videogame screenshots, and the missing interface with photo upload sites keeps SnapDraw out of the big leagues just yet. Your choice in app will depend on what you'll be doing with your captured screens.
Note: The trial version has a watermark on all screenshots in the lower right corner, has nag screens and lasts for 30 days. The full version costs $30.