Here's one I've been playing for a few days. From the home page:
Join over 7,500 active players and try your hand at creating an online drug empire! Buy your favorite narcotic at one subway station and sell it else where for profits! But that's not all, the more you make, the more you can pimp-it-up with bigger, badder jackets, weapons and armor. You can use these to jump other players and steal their goods or increase your trafficking volume.
Then take it a step further and form an online drug cartel with your friends or people you meet in the game; build up purchasing power, and increase your odds of successfully jumping weaker dealers! And in the end, work your way to becoming the cities most powerful, and richest dealer!
Oh yeah... did we mention that the game is free to play! Good Luck!