> As of July 2015, there are at least 522 known cryptocurrencies,

Realistically: sort by popularity in descending order and keep the top 3.

>tens of reliable cryptocurrency exchanges

...until exchange will either get hacked or owner will ran away with customer's money...

> and a growing suite of services specifically facilitating financial operations in cryptocurrencies

These are great business models. Just like selling shovels to gold diggers - never fails during the gold rush.