During my regular reading of tool lists (like Scott's) I've seen this tool called Cropper.  My first thought was that it was a scaled down version of a image editing tool.  I was wrong...way wrong.  It does just was it says, it Crops screenies and that's about it.  Not to downplay it at all.  It's a great little tool that does the job very well.  I especially like the options of copy to clipboard or output to an image file and that's after assigning a shortcut-key.

If you do any documentation where screenies are required then this tool will help you a ton.  Just crop what you need and you've got it.  No more alt-prtscn and pasting to something else to only get the piece you need.

Thanks Brian!