ScreenShotTimer20s is a utility that takes screenshots at regular intervals, with the intention of using them for doing things like generating time-lapse videos of game development.
Usage is simple - download and run the executable! It will create uniquely named screenshots in a new folder named snapshots. If you quit the program and start it again, it will not overwrite earlier screenshots. To change the interval at which it takes screenshots, simply rename the executable (select it and press F2). Examples:
While the utility is running, you can pause it as well as increase or decrease the sampling interval. Screenshots are saved as lossly compressed .png files.