what are some good online RPG's like perfect world and fly for fun that have mods or cheats i can use?

Real for-profit MMORPG's do not have Cheats, many of these games have private servers hosted by individuals who mod out the game for fun. However if you want the next best thing, games like fly for fun and perfect world have item malls, a good way to make money for the developer, but a great way to unbalance the game. In those games you become more powerful for the ammount of money you can throw at them. So, just buy some Gpotatos and buy something to uneven the odds.

My opinion: You should not want to cheat. Being better then someone fairly, is much better.