Quite a few blogs are linking to these fake eyeball stickers, though I haven't been able to track down if any company is actually selling them. Nevertheless, they're a good idea if you want to take a nap at work while pretending to be working. Just place the stickers over your closed eyes, and no one will be the wiser. (via J-walk).
Update: If you really want to buy some eyeball stickers of your own, Roylco sells them. They're not exactly the same as the eyeball stickers in the picture above, but they're close. (Thanks to Becca for the heads up about this.)