Normally you take screen using the standard PrtScn and Alt-PrntScn keys but MGrab will intercept the saved data as it is sent to the clipboard and put it into your chosen folder as a BMP or JPG file leaving the clipboard free for you to take another screenshot.
Its allows captures in BMP and JPEG format, provides thumbnails, and also takes multiple screenshots. You can also send your saved shots to your favourite editing programme and delete single grab files in one go.
An easy way to take screen shots.