Woop MMORPG fan right here
I've played a fair few only ever stuck to a small amount though! Ones I've played (from memory) are below with a mini review ^^
Runescape - Good for a short while... well good in the early days! Now you just get tons of hackers beggars, perverts and generally nasty people there. The skill system is excellent, its free to play and no need to download. However it IS free but you have to pay if you want extra features. And by extra feautures I mean quest updates and 75% of the game. For a free member nothing new ever gets done!
www.runescape.com for this one
Guild Wars - Free (apart from disk) Don't really know what to say about this one. Wasn't really my cup of tea. I found it laggy, repetetive and rather boring.
WoW [currently playing] - I really love this and it's not as bad as it sounds! After a while it starts to get boring but there are so many different character combinations and so many lovely people that you don't really get too bored. Plus the HUGE map is a bonus! The only bad thing is that I'm not really sure whether it is good value for money. Use your own judgement on that one.
FlyFF (Fly For Fun) - Fantastic game, however it does get a little boring and repetetive after a while. Great graphics and has a unique feel, Tales of Pirates looks very similar, I may start playing that soon too! Free to play and download but you can pay for extra items. This is made by GPotato and I suggest checking out their other MMOs too!
http://flyff.gpotato.com/ for this one
GunZ Online (also known as "GunZ - The Duel") - This isn't an RPG, it's an MMOFPS but still it's pretty fun, pretty engaging, incredibly competetive and has a reasonably nice feel. Last time I played it was free but I think now you have to pay for the extra special items or something. Be careful on this one because you really get into it and can quite easilly find yourself getting stressed out and screaming at the screen!
http://gunzonline.com/ for this one
I'll add more if I think of any, cheers for reading and I hope this has helped some of you out ^^