Wikipedia
Lightscreen
Lightscreen is a lightweight screen shooting application for Microsoft Windows used to automate the process of saving and cataloging screenshots. It operates as a hidden background process that is invoked with one (or multiple) hotkeys and then saves a screenshot file to disk according to the user's preferences. It has no built-in editing or annotation tools. Lightscreen has features to set a delay time and save screenshots in multiple image formats. A portable version is available