I also played Diablo 2 and looking foreward to Diablo 3(potential gold mine).
Thing that bothers me is if they will make items in diablo 3 soulbind like in World of Warcraft(that means that items obtained by you cant be traded to anyone else besides your party),that could ruin the whole diablo *item selling concept* which d2 had.
I play World of Warcraft and today 1000 gold is like 1.5euro or less 1.3e.What eniviD said boting on mass lvl is the way to go for the real money.
When we go back at 2005-2007 1k gold in WoW was like 10+ euros and whoever had bots,mules and other gold exploits made really huge money.
Also the gold sites buy cheap gold from us players and resell for higher.
Today the most profitable in WoW would be powerleveling,honor grinding and getting the starter pvp set,Arena services and selling characters with special moutns,titules and achievements.There is also money from writing quality guides for games.
Yesterday launched a new MMO called Rift,so maybe some of you should check it out,being first to offer a service is a plus always.
Private WoW servers,WoW,Rift,Terra, and upcoming Star Wars MMO and Diablo 3 could be a good money income.
I also heard that Blizzard is working on Marketplace service inside battlenet where people can sell their premium Starcraft 2 maps and mods.