Already spending them... I wait until I have enough to buy new gaming equipment for my PC...
I was thinking of saving up for another 7970, but I'd like to get into water cooling... so I dunno what I'll do next. Maybe if I have enough by the time the 7990s are around, maybe one of those.
I'll always save "some" in case their value explodes, but I like real objects vs the uncertainty of where bit coins are going to go. (I also sort of do this with real money, too, given that I don't trust people in charge of our economy).