In general I agree with Darkman. A more in-depth research into Bitcoin, or any crypto currency, is necessary in order to understand how it differs from fiat currency; money that is money only because the parasites say it is. The [enforced] scarcity of Bitcoins will be part of what gives them their value; the parasites can't steal their value by arbitrarily creating more of them.
Some of the links I included explain how more places are beginning to accept them, so you can use them even if you don't sell them for your local currency.
Looking at the BTC network today, it would not make sense to buy one or more HD7970's for mining; two or three months ago it still did. Were I to cash out now, that HD7970 would have only cost me $200-$250. Should BTC double in value (probably more likely than crashing, but both are possible), the card would be "free;" and that is after electricity costs.
I don't believe anyone here is suggesting that mining BTC is enough to earn a living wage (or anywhere near it), but if it offsets the price of a [substantial] graphics card upgrade? It won't after this summer, but for the next few months might still be worthwhile if your electricity costs aren't too high.