Never Winter Nights on AOL back in '97 (cost $3 an hour to play, $900 a month gaming bills, outch).
Ultima Online (although I sold stuff in UO ... I had a fleet of 25 computers scripting 100s of accounts 24/7 ... on a good month I'd make 10 grand a month selling in-game gold ... made all that NWN cash blown back and then some).
Built a search engine for items found inside vendors on the game, used it as a portal to sell UO gold. Finally competition from chinese sweatshops and hackers who made gold out of thin air ruined the value of gold and it didn't make enough profit anymore. Sold off my search engine (finduo.com) for 25 grand and moved to the Philippines.
For fun I used to play DAOC (dark age of camelot) ... though they nerfed all my toons so I finally stopped playing games for fun.
Looking for to guildwars 2 ... beyond that I don't mess with anything anymore.