lots of mmorpgs are very boring once you play them a lot. flyff is a great game and I play it heaps. as for runescape, add filth25 and ask me to let you borrow some items. i am a member so I am happy to help you.
I am very interested in this too. I used to play World of Warcraft, but had to get myself off of it, I was playing too much. But I want to know if there are some good, free ones around to spend time on. Hope some good responses come.
Would you include MUDs (text only) as MMORPGs? There's hundreds of those available, mostly free. Offhand, I'd recommend Aardwolf, BatMUD, or any of the Iron Realms games. Or have a look around on TopMUDsites.com or mudconnector.com.