For those curious about the SFW-ness of the link it's the homepage for an online casino site accepting bitcoin.

I never understood why people put money into satoshi dice. In my opinion, betsofbitco.in is way more fun, though admittedly slower paced. Similar to intrade.

Drugs, gambling...get hookers in there, and you'll have a legit currency. ;)

No, seriously, once a currency gets to the point hookers accept it, it's indisputable that it's real.

Or poker (https://sealswithclubs.eu/). If you snoop around on the twoplustwo poker forms you will see there is some interest and decent reviews of the site. I imagine for someone that gambles regularly, it's easier for them to leave their bankroll in bitcoin rather than continuously exchanging it back to USD or whatever.

I'm no economist but this is how I see a fiat currency like bitcoin deriving value. Even if no one used bitcoin for a currency, there would be some people who would be interested in buying some just for the novelty of it. That alone gives it a non-zero value. From there, if it has the properties of being a useful medium of exchange, people will use it as such. Over time, the value grows as the amount of "float" (value exchanged into it) grows.