Now, if you plan on giving up WoW... i RECOMMEND that you download the free trial of Lord of The Rings online... now when i was giving up on WoW (yea i dont play retail anymore i just test WoTLK now...) i downloaded it and i was AMAZED! Its just so cool! Now heres a list of stuff if ur gonna give up WoW, some of them are not MMos:
LOTRO
Tabula Rasa
Age of CONAAAAN
Halo 2 or 3 if u have xbox
Buy a PS3 and play Assassins Creed
Starcraft 2 (when it gets out)
Now i did all of this... and its just so MUCH COOLER than WoW! I mean my WoW Addiction is over and i have very good grades anymore and now if someone tries to beat me up i use some moves from Assassins Creed and kick his ass roflmao. You can also play Assassins Creed on PC i actually didnt buy a ps3 but i said so, so that u can play more games.
About Halo 2... well this game plain rocks. I played multiplayer with my friends and i killed them all and i was like... OH ITS SO COOL.
Tabula Rasa... this game OWNS (ive not actually tried it fully yet but its just soooo cool)
About Starcraft 2, now this is the one i havent tried but im sure ill like it, as well as u. Trust me if u have played starctaft/WC3/ WoW u are gonna love it. Blizzard makes masterpieces.
From all of these... well the winner is... actually a tie.
HALO 2 AND AGE OF CONAN!