Just finished Julian Dibbell's Play Money: Or, How I Quit My Day Job and Made Millions Trading Virtual Loot. I loved how Dibbell takes you along for the ride from player to "player;" chapter by chapter you're ever more engrossed in the micro-economics of what he's up to. And by the end you're thinking to yourself "yeah, there's potentially real economic value here, there's real work being done, there's even cheap, outsourced Chinese labor producing goods in these worlds and heck, ever since we ditched the gold standard the greenback's just as much a collective hallucination as Britannia gold." And then Dibbell brilliantly leaves it to an IRS agent (of all people), to pull the magic carpet out from under you and send you crashing back down to reality:
"And as soon as it starts holding value, you're gonna wish it didn't, you know what I mean? Because how are they going to keep track of it? The game company'll have to start sending out 1099s for every time somebody gets a gab of grapes or a gold coin or a shiny emerald -- the game companies are going to say we don't want to do this anymore, because we're not making that kind of money. And your online subscription's going to triple. Just to keep the paperwork. You'll see the game collapse the moment they start putting value on that."
Not to ruin the ending for you or anything.