One reason more why not to depend on ad providers, like Google is:
"The popular wiki TV Tropes, a site dedicated to the discussion of various tropes, clichés and other common devices in fiction has suddenly decided to put various of its pages behind a 'possibly family-unsafe' content warning, apparently due to pressure by Google withdrawing its ads. What puzzles me most is the content that is put behind this warning. TV Tropes features no explicit sexual content, and no explicit violence. It does of course discuss these things, as is its remit, but without actual explicit depictions. In fact, something as relatively innocuous as children being raised by two females, whatever the reason are put behind the content warning, even if the page itself doesn't take a stand on the issue, merely satisfying itself by describing the occurence of this in fiction." [1]
So, if WMF ever go with ads, it should be its own provider.
[1] http://yro.slashdot.org/story/10/11/07/2348259/TV-Tropes-Self-Censoring-Unde...