SnapNDrag lets you take a screenshot by just clicking a button and
dragging the resulting screenshot off.
For example, to email a screenshot, you would drag the screenshot
from SnapNDrag to the Mail application. It is that simple. No
hard-to-remember key combinations, no file conversion to deal
with, no file dialog boxes to navigate, no temporary files to
erase later on.
Supports PNG and TIFF for times when image quality cannot be
compromised. Or use JPEG with adjustable quality for smaller file
sizes.