On: SparkFun CryptoShield

[beagle3]

For practical uses, it's probably better to get a $50 YubiKey Neo and plug it into the USB port of a Raspberry Pi ($25 if you get the Model A).

Crypto is easy to get wrong in every corner - and using a Neo+GPG it's more likely to actually work (plus, it's FIPS-140 certified)

For learning, this seems cool - although I don't see the ways in which it is more educating than software only crypto.