The only MMO I ever played for more than like a week is Dungeons and Dragons Online. Saying that I played it is probably an understatement. DDO consumed my life for most of the time that I was an active player. There were several occasions where I played the game for 48 to 72 hours straight, stopping only for food and a few hours of sleep every afternoon. I'm sure this comes as no surprise - MMO's are addictive by design, so, yeah.
On the server I played on there was a guy named Sto. Seems like a weird name for a character, right? Well his last name was Rage. Sto Rage. Storage. Get it? The name comes from the common practice of having a "storage toon," which is an alternate character that you keep around only to hold on to your loot and other vaulables so that your main character's inventory is freed up to collect more treasure. I never really knew the guy personally, I only met him in passing once or twice. But I saw the guy in the marketplace a lot.
See the way DDO works is really different from what you expect from an MMO. If you're picturing WoW, you have the wrong impression. Instead of the world being a huge expansive landscape with cities here and there and tons of wilderness and dungeons full of enemies in between, DDO basically only has one city. There is no wilderness like you have in WoW and its clones. Every single quest and raid in DDO takes place inside a dungeon, and when you and your party go into a dungeon you enter your own private instance of said dungeon, with no other random passers by interfering or PVP'ing you or something. (DDO has no PVP) In many cases a "dungeon" will be a forest or a jungle area or something, but the important thing is that everything in the game is instanced.
Because of this design, DDO only has one city. It's called Stormreach, and at any given time a hunge chunk of the server's population will be there. The city is made up of several different areas and each area has its own public chat channel. But the biggest section of Stormreach, and the most populated, is the Marketplace. If you type something in public chat in the marketplace, your message will be read by a LOT of people.
So back to Sto. Like I said I never really knew the guy so I don't know the full story behind this, but at some point Sto must decided he wanted to make money. A lot of money. He was already somewhat rich, but not really rich enough. He didn't want to do the usual grinding/crafting rigamarole that you're supposed to do to get rich. Instead, Sto decided to set up a lottery.
Here's how it would work. Sto would post in public chat in the marketplace, bascally advertising his lottery. You could buy any number of tickets, at a cost of 1 platinum per ticket. (DDO uses platinum instead of gold. Long story.) Sto would then give you a block of numbers. For example, if you bought 1000 tickets, you might get 12,300 through 13,300. Sto told you what numbers you got and he also kept track of it himself.
Every saturday at a predetermined time, Sto would roll randomly to determine what the winning lottery number was. DDO has a system where you can roll "dice" in chat by typing /roll and then some amount of dice (1d4 to roll a single four-sided dice, 10d10 to roll 10 ten-sided dice, or whatever) Sto would roll a one million sided die, and whoever had the ticket with the matching number won the lottery.
You might be thinking, "Obviously this is a scam. He either doesn't roll and declares that nobody won, or he rolls in secret and says the number of some ticket that nobody actually has." Well, no. On Saturdays when it came time to roll for the lottery, Sto would start a public raid group, with the description in the "looking for more players" post explaining that this raid group is for the lottery. Once Sto had a full sized raid group (12 players is the most you can have in DDO) Sto would roll the d1000000 in the raid party's chat channel, so he'd have a dozen witnesses who could veirfy what the winning lottery number was. Sto would then announce who the winner was and send them a PM as well, telling them they had a week to claim their prize. Since the winning number is public knowledge and everyone knows what lottery number is theirs, as long as the person who bought the ticket was paying attention they'd be sure to know to claim their prize.
The prize was one million platinum. Now, if you've seen other MMO's, you might not think a million is a lot of money. It doesn't sound like much when you compare it to the insanely inflated economies you'll find in most games, where high-level loot sells for like ten billion gold in an auction house. But DDO's economy is actually fairly stable, all things considered, and a million platinum is a lot of money! Just for reference, the most amount of currency any one character could have is about 4.3 million platinum. (The game calculates the base unit of currency as being a copper piece, which is worth 1/1000 of a platinum. Technically your money cap is 4,294,967,296 copper pieces, which appears to be a 32 bit unsigned interger. I'm not sure why the game is programmed like this.)
The mods were aware of the lottery, and they let it go on. According to the game's official terms of service, as long as Sto's little project took place eneitrely within the game and used no outside means, it was fully acceptable within the rules. And Sto's lottery actually gave away a proper fortune, assuming people actually bought the tickets, and assuming the winner came to collect their prize. I talked to Sto one time, when I was in the marketplace trying to hock some cosmetic item. He said he actually made very little money off the lottery, and I can kind of see why. If he sold a million tickets or more, he'd be guaranteed someone will have a winning ticket. If he sold less than a million tickets and someone won, he'd be out a bunch of money. I think he mainly kept doing it as some kind of habit or tradition. Eventually Sto stopped showing up in the marketplace, so I assume he stopped playing. I don't play anymore either, so I have no idea what ever happened to him.
Sto also had some kind of casino slot machine setup, where someone could send him a private tell with three die rolls, and if they matched they'd win money. I'm not really sure how that worked because the player would have to put money in the slot machine first somehow. I don't think his slots were nearly as popular as his lottery.