I should've added, the prices have to be tied to some value. So for example, what you could do is give everyone 10,000 play dollars at the start, and they can

I should've added, the prices have to be tied to some value. So for example, what you could do is give everyone 10,000 play dollars at the start, and they can buy/sell whatever "sites" they want at the going prices. But every day (week?), there's a payout -- if you own one share of site X, and site X is #n in the rankings, you get a dividend of say 50,000 - n cents. Then if I think that site X will be in 1000th place, I should be willing to pay up to $490.00 for a share, because that's how much I expect it to pay off for me. Something like that.