Gadwin PrintScreen lets you send a captured screen directly to the printer, copy it to the Windows clipboard, save it as an image file, send it via e-mail (if you have a Microsoft Outlook profile set up), or perform any combination of these tasks. Not bad for a freebie.
You can capture the full screen, the active window, or a rectangular area. There's also a Client Window selection that the documentation says selects "the client area of a user selected window"; I didn't see any difference between this and Current Window. PrtSc is the default hotkey, but you can select another if you wish.
Gadwin PrintScreen worked well in my tests, but the interface was a bit confusing. When you press the hotkey and begin a screen capture, the program shows you a preview and offers four options: Change Destination, Continue Output, Cancel Output, and Help. The output selections let you continue or halt the screen capture; Help is self-explanatory. The Change Destination button, however, leads you to the program's main interface, where you can indeed change the destination (send the image to a file, print it, and so on); but this is also where you access the program's other settings. Preferences lets you change the hot key and tweak other settings; Source allows you to choose full screen capture, window, and so on; and Image lets you select the output file format, and more.
Minor quibbles aside, Gadwin PrintScreen costs nothing and does what it's advertised to do. If you spend a lot of time creating screen captures, you'll want to give this tool a try. It's not anywhere near the level of an expensive program like SnagIt, but it does the job. Gadwin also offers PrintScreen Pro, which adds image editing for $25.