Note that it is illegal in the US to use an alternate currency. The second this becomes popular, the feds will raid it and shut it down. See Liberty Dollar, e-gold, etc. Casino chips are specifically exempted from this rule, but only inside a casino.
e-gold was busted for violating Know Your Customer money laundering regulations.
Alternative currencies can be legal-- see, for example, Disney Bucks (paper currency issued by Disney) or Ithaca Hours (oldest local currency in the US, going since 1991).