Once again the Arduino platform has been used to replicate something incredibly fascinating, and in this example we have the Enigma cipher machine used between the 1920s and 1940s. This device was used to code and decode messages in peacetime and also during World War Two. You can find out more about the Enigma machines through Wikipedia. Moving forward, Instructables user "ST-Geotronics" have published details of their own Arduino-based version, using a Mega-style board due to the increased amount of I/O required.
As you can see from the image above, the replica is somewhat true to the original and uses some LED displays to emulate nixie tubes for added interest. Even if you're not going to make one, it's a fascinating device of which you can find out more here. And for more. we're on twitter and Google+ - so follow us for news and product updates as well.
If you're looking for an Arduino-compatible board with plenty of I/O to drive many buttons, LEDs, keypads and more - consider the Freetronics EtherMega:
Quite simply the EtherMega is the fully-loaded Arduino-compatible board on the market today. Apart from being completely Arduino Mega2560-compatible, it includes full Ethernet interface, a microSD card socket, full USB interface, optional Power-over-Ethernet support and still has a circuit prototyping area with extra I2C interface pins. So if your project is breaking the limits, upgrade to the EtherMega today.