Greenshot is a simple, open source screen capture tool that will quickly create and save the grabs you need.
The program can capture regions, windows or the entire screen, and in a couple of clicks you can automate what happens next. The image might be sent to the clipboard or printer, for instance. You can have a Save As dialog pop up, or even leave Greenshot to automatically save the file using your preferred settings, a real timesaver if you've plenty of grabs to do.
By default Greenshot will open your screen grabs in its own editor, though. This allows you to annotate images with rectangles and ellipses, lines, arrows, text boxes or more. And when it's finished you can save the file, print it, despatch the image by email, or more, all in a click or two.
It's all very easy to use, reasonably lightweight (Greenshot consumes around 7MB of RAM initially), and very configurable - if you don't like some aspect of the program then it can probably be changed. Capture type, destination, printer settings, default file name, JPEG compression, whether or not to include the mouse cursor in a grab, all these options and more can quickly be adjusted to suit your requirements.
Build 220.127.116.11 is a maintenance/ bug fix release.