If you were in doubt about World of Warcraft's popularity amongst MMOs, the updated subscriber numbers over at MMOGChart will set you straight. The pie chart above shows the market share, as of May 2006, of subscription-based MMOs; the huge blue slice taking up 50.6% of the market is none other than Blizzard's behemoth.
While a number of smaller games have some slice of the pie, the MMO world is dominated by Lineage, World of Warcraft and Runescape -- the latter has been racking up subscribers recently.
In this illustration of subscriptions with time, the bright green (almost vertical) line is, unsurprisingly, World of Warcraft. Interestingly, the growth here implies that WoW's market share is caused by many new players, rather than players deserting other MMOs for it. The market share is large, but the market is being expanded by WoW.
What will happen when the next wave of MMO games hits? We didn't see anything at E3 that looked ready to snatch the crown from WoW, but the influx of players to the MMO genre means that plenty should seek out new titles to try sooner or later. Like it or not, WoW's dominance is reality, and MMO designers who want to attract players to their games will have to take it into account -- players suckered into paying a monthly fee to Blizzard won't want to pay two fees at once, for example.