Stalker - shadow of chernobyl was never ment to be a massive multiplayer game afaik, the only thing massive there is the landscape (like farcry but for real this time), and multiplayer was ment to be made, but as mentioned the landscape is way too massive for it to work, max server at 32 players and they'll never find each other.
Morph, I was a team member on a mmorpg project, well actually I still am, I'm just hibernating, till I get my inspiration back. May have heard of the game, it is coming along mighty nice
www.planeshift.it
And Planetside IS the greatest mmofps there is, but I agree with husk, the story should be bigger (now it's more like a background story not real epic story that you are part of), the continents are vast but should get some major cities where battle could take place, should have more technology like in NC and skills more than combat related, so that it had some tradeskilling but still would be battle / pvp oriented.
There are alot of RP outfits in Planetside, ours was the rag tag squad of high comman guardians, we were pretty big and owned most of the time, becaue we made simple plans with backup from other outfits. Once we owned a whole continent and kept it mighty long, before the timezone switch which led to most of our ppl logging and the frikkin terrans came back to kick our ass. Vanu for ever!