This may be the weak point of these crypto-currencies. The proponents market them as scarce commodity but in reality you can just think today of another scheme like that.
So why is it booming? It is booming because it is booming. It's a positive loop that will end when the new comers stop coming.
Litecoin just hit 30usd, Peercoin nearly at 4usd.
http://coinmarketcap.com/