Both Facebook and Google+ are using your profile pictures to tie into ads. This helps those ads seem more appealing to your friends since you Liked or +1ed those companies in the past.
Social ads are easy enough to disable though.
In Facebook go to Settings -> Ads and click the ‘Edit’ button for ‘Ads and Friends.’ Then change the drop down to ‘No One.’
In Google+ go to Shared Endorsements under your profile settings and uncheck the box that says ‘Based upon my activity, Google may show my name and profile photo in shared endorsements that appear in ads.’
Social ads make perfect sense from a business standpoint as it’s builds trust between my friends and an advertiser if it looks like I endorse them.
The downside of course is that I don’t endorse any ads and I have no idea where my photo is being shown. In all cases, it should be shown to just my friends, but I’m still not sure I’m comfortable with it.