Tax: CEO already posted the thing about taxes: GPUcoin is considered as a commodity and when you buy GPU with GPUC, you are exchanging commodity with commodity, it is tax free.
For those in the USA, that is very dangerous advice. A graphics card is NOT a commodity, it is a realization of gain on the investment of the cryptocurrency being used to exchange. Your costs to acquire GPUcoin is considered your basis, and any difference between your cost to acquire and the cost of the card is a gain.
I suggest further reading here.
http://www.reddit.com/r/Bitcoin/comments/1uccfz/i_am_a_tax_attorney_here_are_my_answers_to_the/Despite the fact he's a tax attorney who arguably could be looking for clients, my own tax accountant his given me similar advice as well.
OK, so buy gold with your coins. Commodity for commodity.