You're at work, 20 minutes away from a really important meeting, and realise you've left a vital file on your home PC. Oops. Normally there would be nothing to do but prepare your excuses, but if you'd installed TweetMyPC beforehand then there could still be hope.
Leave this ingenious utility running on a PC and it'll constantly monitor the Twitter account you specify. If you want a particular file, just send it a tweet specifying the file path and name and it'll be emailed to you at an attachment. It's quick, easy, a potential life saver, but only one of the useful commands TweetMyPC supports.
If you're away from home and come across a big file you'd like to download, for instance, then you don't have to grab it now. Send a tweet with the file URL to TweetMyPC, it'll download the file onto your home PC and it'll be waiting when you get back.
Maybe you'd like to see your desktop? Send the "screenshot" command to TweetMyPC, it'll take a grab of your screen, upload it to Twitpic and send you the URL.
And there are other commands to reboot your PC, shut it down, retrieve its IP address, list running programs, close any you don't need, and much more. You can even create custom commands to launch whatever programs you like, all via a simple tweet sent from just about anywhere in the world.