I found a super cool Kickstarter project that will exercise your history, math, cryptography, and gadget nerd all at once! It's called the Open Enigma Project by S&T Geotronics, an open source recreation of the German Enigma encryption device from World War II. Enigma was an incredible mechanical encryption machine that was cracked by the allies only through a remarkable combination of luck and mistakes on the part of the Nazis. Better yet, assuming you're not a Nazi, it was exploited by the Allies to remarkable effect because the Nazis knew it to be uncrackable. OK, so enough history: this Kickstarter project will allow you to get or make your own (depending on your funding level) electronic Enigma reproduction that will allow you to create your own encrypted messages. It can interface with your computer through USB, and future options could include WiFi and the ability to encrypt your router traffic. What?! Too cool!
Check It Out: Fund a Usable Enigma Machine Reproduction on Kickstarter