A screensaver to send your display to sleep.
I poked around a bit looking for something that did this, and couldn’t find anything, apart from some sample code using a private API to send the display to sleep, so I whacked that into a screeensaver.
https://sites.google.com/a/explanatorygap.net/misc-sw/files/SleepSaver.saver.zip
This does use a private API and thus could do anything. No warranties, may destroy your machine, etc etc [...]