EVE online.
A MMO i been playing since mid 08 paralell with IL-2 46, last summer had a riot of it's subscriber base regarding a new expansion in the spring of 2011 (wich are all free btw,but game is sub based).
The developers announced that they would be concentrating development on the "in station" things instead of the main "flying in space" part of it for a while.
Went much deeper than that, but resulted in mass rioting both ingame and outof it. Ingame thousands of players gathered and started shooting at a monument in pure protest.
Long story short, the playerbase saw no other option for stating their oppinion and get the game back on track and get the developers to stop just adding new shiny things and start working on repairing features that have been ruining gameplay for years than voting with their wallets showing their discontent with game direction and future plans.
http://http://massively.joystiq.com/2011/11/16/eve-online-monument-commemorates-the-summer-riots/ Will just post a link to massively.com, wich for the interested can lead to propper pages to read for those interested.
Man those were some intense months
BTW: Not a sim, totally missed the main point :-S Still interesting to see how CCP (the developer) quickly changed course as soon as playerbase started voting with their wallets.