The program seems to be no longer updated. Last version, 2.7, released in November 2011, can be still downloaded from the official website.
DuckLink Screen Capture (AKA: DuckCapture) comes with four capture modes that make screen capture easy! Capture a window on your screen, region of your screen, or the contents of a tall web page that scrolls. Don’t waste time cropping your captures. DuckCapture exactly what you need.