Similar to how the word “forex” was coined, use ”cryptex” to refer to crypto currency exchange
Bitcoin, then Litecoin and now Dogecoin. There are literally 100s of crypto currencies. Most of them will probably fail. Bitcoin is on the cusp of becoming mainstream, with an NBA team (Sacramento Kings – http://www.wired.com/business/2014/01/sacramento-kings-bitcoin/), and some major websites accepting them as payments.
If you need a site to keep track of and get the exchange rates between all the crypto currencies here it is: http://www.cryptocoincharts.info
The latest fad is Dogecoin. The coin was started based on an internet meme and uses a cute Shiba Inus dog as the logo. A printing, a doge coin is worth 0.00015 USD. A large amount was sent to Jamacian bobsled team to fund their trip to the 2014 Sochi Olympics. Currently, the easiest way to buy or sell Dogecoin is to get bitcoin, and then exchange it for dogecoin.