In which MMOs is the purchase of in-game items with real money allowed?

For example, Blizzard explicitly disallows the buying and selling of gold or other in-game items within World of Warcraft. Which MMO games allow these transactions?

From gaming ChiCubed

• Not that I would really call it a MMO, but Second Life Lindens (in game currency) trades for real money on their website.

  tzenes : Massive? Multiplayer? Online? Its definitely an MMO; in fact, its very much a role playing game too.
  From gnarf

• If you're referring to virtual goods, quite a few games allow that.

  Actual cash <> [in-game currency here] transactions are a little rarer, but some do exist. MapleStory, for example, has meso bags in their Cash Shop that allows you to buy set amounts of meso for some amount of cash.

  From Corey

• Many of the Korean MMO's will do something of this nature.

  For instance, I used to play Flyff, and you could upgrade with cash.

  You can also do something similar in Battlefield Heroes, which is more of a persistant/instanced shooter I guess.

  From espais

• EVE supports it in a slightly roundabout way.
  You can buy PLEX (a month worth of subscription) with Real Money and then sell it in-game for in-game money which you can then use to buy anything you want. Very slick!

  From Task

• Entropia Universe probaly also qualifies, as In game currency can be exchanged to real money and vice-versa, for a fixed exchange rate.

  From alexanderpas

• A Tale in the Desert and Wurm Online.

  From clweeks

• This is quite a broad question, but here are some of the more mainstream answers whose status may have changed since this question was originally asked:

  • EverQuest II has a free to play mode, but it is heavily restricted from what you can do with a subscription account. Of course, it also has a store you can buy things for real money, including the ability to play as certain races.
  • Dungeons & Dragons Online is free to play and has a store to buy in-game items.
  • Lord of the Rings Online is free to play with with LOTRO store. The difference here is that it's possible to earn Turbine Points (the game store's currency) in game in addition to buying said points for real money.
    Having said that, LOTRO's free accounts are more limited than their VIP accounts.
  From Powerlord