A newer version of FastStone Capture is available.Or, Learn More About FastStone Capture
Just like other stuff from Faststone, it's extremely small but extremely useful. The program's always-on-top. Capturing is amazingly easy and accurate at the same time by means of a magnifier. The magnifier intelligently goes to a corner of the screen that you don't need while capturing. It captures windows (active, scrolling, or else), objects, regions (rectangle, polygon, or freehand), and full screen. The result can be set to be opened in a native editor, copied to clipboard, or saved to a file. You can even set it to save the image file without asking you. Save dialogue, however, is Faststone's standard one, which I believe is the best thing possible. I use it's colour picker too, and this part is just perfect too. You can use the editor and the magnifier independently. Other options include customisable captions, edges and watermarks, and a few interface skins. All this is 1.2MB. Unbelievable!
It can't capture scrolling pages of Firefox smoothly, though as I've seen all big names (like Corel Capture or SnagIt) suffer from the same problem. The previous version was free for personal use. This new one is not.