Cropper is a screen capture utility written in C# on the Microsoft .Net platform. It makes it fast and easy to grab parts of your screen. Use it to easily crop out sections of vector graphic files such as Fireworks without having to flatten the files or open in a new editor. Use it to easily capture parts of a web site, including text and images. It's also great for writing documentation that needs images of your application or web site.

It doesn't really matter what language the tool is written in, but this program  happens to be one of the smoothest screen capture utilities around, and it happens to be written in C#. I've been using it for months, and I have no plans to replace if for another cropper/clipper/capture tool.

It's available on CodePlex and there's also a Cropper Plugins project there with a bunch of more or less useful plugins :)