This thing is similar to Cropper
but has the unique ability to let you do freeform screenshots.
What is Snippy?
How often have you carefully selected some text from a Web page and copied it to an email message? Snippy makes this a snap! Simply click on the little Snippy icon in the taskbar notification area, and mark out the region of the screen that you want to copy — that's it, you're done! The cut-out image will now be in your clipboard, and you can paste it in another application.
If you are cutting out a portion of an Internet Explorer window, the URL will also be copied to the clipboard; this makes it very convenient to select something interesting on a Web site and send it out in an email message.