MMORPGChart.com

[Bodhesatva]

I visited this site constantly some time ago, but then it stopped being updated for some time. The owner has begun updating it again, and WoW's dominance has continued to grow. By subscriber base:

http://www.mmogchart.com/Chart1.html

You can see that not only has WoW continued to grow at a steady pace -- it clearly hasn't peaked and hasn't even slowed -- but also that all other MMOs on the market are actually shrinking, save Runescape and a few titles way down the subscriber chain. 

http://www.mmogchart.com/Chart7.html

Doing a quite mental count of what "all others" could consist of, I can confidently say that there are at least 30 games listed here, but it's very likely there are more. WoW's market share: 63 percent. Every other game in the genre: 37 percent. This market share is up from the same time last year, when it was closer to 55/45.