Here's a graph which I found extremely interesting. A person has been researching the growth of MMOGs subscriptions of many titles released since 1997, the results of which are displayed in a nice graph...
Obviously it shows that it takes YEARS for a MMOG to even reach some sort of peak, and what is pretty alarming is that you can see a lot of the relatively new ones (under 2 years old) are already on the downward spiral.
It looks like Final Fantasy XI is doing extremely well - their numbers are way off the chart (I'd hate to see the numbers that Lineage is getting). It's a shame about Eve Online - I thought more people would be more in the Elite style space combat/trading kind of genre. The game does look extremely nice too.
Anyway, it's pretty interesting, and you can [url="http://pw1.netcom.com/~sirbruce2/Subscriptions.html"]read up on the analysis here[/url].