It's free and easy to use, but this Firefox extension for copying and saving captured Web shots only delivered half its functionality for our testers.
Once you install Screengrab, it can be accessed by clicking on the status bar icon. There, you have two options--save and copy. Under both options, you can choose what view you want to grab, from the whole page to a selection that you determine. The Options menu gives you a choice of image formats (PNG or JPEG), as well as a preferred capture method (Java or Gecko Canvas). Using the save feature, and both image formats, we successfully saved the entire Web page and the visible page. We found the crop tool a bit awkward to use when we made a page selection. It disappeared as soon as we let off the mouse; we barely had time to confirm the selection. The copy feature did not work for us, despite trying it repeatedly. If you want to paste the image elsewhere, you'll have to do so outside the program using the image you save.
If you're looking specifically for the copy capabilities, you can skip Screengrab. If you just want more control than you get with Print Screen, this freeware will fit the bill.
Screengrab saves entire Web pages as images. It will save what you can see in the window, the entire page, just a selection, a particular frame, basically it saves webpages as images.