There are times when we are a bit lazy to go to the Mac to put it to rest, a situation in which it would have been a real luxury to know this trickAlthough the downside is that we have an Apple Remote.
What you need to do is simply point your Apple Remote at the Mac and hold down the Play button for a few seconds (about 5 seconds). Once the Mac understands the command, it will display a message with a few ZzZz and the Mac will go to sleep.
It's certainly great for those of us who have the Mac near the sofa for example and sometimes we leave it with the screen on or simply working without wanting to. Oh, and it works with both Apple Remotes.