How about: send 0.1 BTC to MtGox for your IP address to be whitelisted for an hour. All whitelist payments would be deducted from your MtGox exchange fees, so this would not cost genuine traders anything.
And you would bury BTC and condemn it to the bottom of the underground, as most people take Mt. Gox as the "standard price" for BTC... so most of people is actually consulting not trading, not all BTC users are speculators or exchangers.
Whitelists are generally impracticable except for small access groups...
Unless MagicalTux splits Mt. Gox in two, one for trading other for consulting.