If you thought spelling out childish messages was the only fun you could have with a calculator, think again. Some incredibly talented hacker who goes by the handle Builderboy has written a Portal clone for Texas Instruments Ti-83 and Ti-84 graphing calculators.
Sure, it's lacking the fancy 3D graphics of the original Portal, but just to emphasize the important part here; it's playable on a damn calculator! Not only that, but Builderboy has actually gone above and beyond the call of duty and created 38 challenging levels for the port. Download it here, and finally look forward to your afternoon algebra lecture. [Omnimaga via Technabob via Reddit]