David Sparks posted an interesting use of Drafts (credited to Milosz Bolechowski; I couldn't find the original on his site), together with noodlesoft's Hazel - a tool that automates tasks on your Mac - to put a Mac to sleep. In essence, Hazel looks for a file named "MB sleep" in a the Drafts folder in his Dropbox folder; when it finds that file, it puts the Mac to sleep with an AppleScript.
I think you might be able to do this with folder actions as well, but I'm not very good with AppleScript. So if you can, feel free to post a script in the comments.

