As far as I know, there's no such thing, only estimates based on e.g. the subscribers base. These estimates are generally in the $1bn to $1.5bn range (edit: per year), and usually on the lower end of that range, since ~2008.
Which definitely does not put any given WoW year at the top of grossing movies (but still in a healthy position, 10 movies so far have gone beyond a billion gross). Still I think a fairer comparison would be to movie franchises, if we put WoW's total revenue around 5~6bn it would rank #2 behind the Harry Potter franchise ($7.7bn) and before James Bond ($5.1bn).
However, I think it's fair to say WoW is an anomaly in terms of revenue. Even more so than billion-grossing movies.
>However, I think it's fair to say WoW is an anomaly in terms of revenue.
Yes, and it may be WoW has to fade away for another MMO to succeed at that level, which limits upside growth for the industry. People who see movies will see multiple movies over the course of a year, but MMO players tend to play one at a time. It's a different model - service vs. product.
And MMORPGs seem to be moving towards "freemium"/"free to play" models: Guild Wars has been from the start, EQ2 recently switched to freemium following what was apparently a successful "Everquest II Extended" experience, Clone Wars Adventures is a freemium, City of Heroes added a freemium mode (City of Heroes: Freedom) this year, ...), and both of Turbine's recent MMOs — D&D Online and LOTR Online — are now freemium, which makes a new WoW (in terms of revenue) unlikely, apart from WoW2 (or Starcraft Online) maybe.
