I'm using FastStone Capture to take all the screenshots for Fantasy Cartography with Adobe Photoshop; you can capture the full screen, just the active window, marquee-selected regions, individual windows within a larger program (like, say, just the Brush window in Photoshop), freehand drawn regions, and scrolling windows. And you can choose the format and resolution for the screen shot (BMP, GIF, JPG, TIF, PNG, or PDF).

http://www.faststone.org/FSCaptureDetail.htm

It's free for non-commercial use.