EVE Online is set apart from most MMOs out there in that players find ways to establish and run large financial ventures within the game. What's interesting is that although such initiatives aren't developer-supported, players still put together banks, IPOs, and other types of investments peripherally to EVE and its game mechanics. The sandbox nature of the game paired with EVE's API allow for ventures of this sort. Dynasty Banking is one choice that players have that's been turning heads of late, but EBANK is the focus of a recent EVE-Tribune piece. EBANK has accrued over one trillion ISK and over 2750 customers, making it -- according to their 2007-2008 annual report -- "the largest financial entity ever seen in EVE."
EVE Tribune had a chance to interview EBANK's LaVista Vista (real name: Charlie Eriksen), who is also a newly re-elected delegate of EVE's player representative body, the Council of Stellar Management. The EVE Tribune piece written by FinnAgain kicks off with one hell of a caveat in the form of a direct quote from one of their staff writers, but it's a good way to begin, particularly given the problems that have been seen in the past with banks in EVE Online. The interview focuses on the policies and safeguards in place to keep any individual working at EBANK from absconding with vast amounts of player-invested ISK, but LaVista Vista also discusses how EBANK puts all that isk to use, and their future plans to establish a stock exchange. If you're interested in the economic side of an MMO, the EBANK interview at EVE Tribune is a good look at what players can accomplish on their own within a virtual economy.