Advertising in Lieu of Game Fees in MMORPGs?

Mat/.Cloud asks: " Am I the only one that thinks it's incredibly unfair to have to pay $20 a month to play a game that I've already paid $50-$60 for? I realize that companies have to charge this fee or they would loose money from the cost of operating the servers. I guess I'm just so spoiled from having everything else on the net being free that I expect this to be also. Then I realized how everything else on the net is paid for... advertising. Would it be possible for companies to put ads in their mmorpg without drastically detracting from the game play? The only reasonably feasible solution I came up with is to have a banner ad at the top of the screen. Do y'all think it would be worth a small sacrifice in game play to keep the games free? Any other ideas on how to insert ads or ways for the companies to pay for their servers?"