Yahoo was paying for referrals to Flickr, both free accounts and pro accounts were rewarded.
But now Yahoo has announced they will close the program
As of April 2013 the Flickr affiliate program will end.
They do hint at rewarding mobile users to join Flickr in the future, so the affiliate program may return with mobile specific actions.
“We will be removing our Flickr actions from the affiliate program at the start of the new quarter on 4/1/2013. At this time, please be sure to remove any Flickr text links and creative from your websites. Note that that this removal includes both the free Flickr sign-up as well as the paid Flickr Pro upgrade.
Though we are removing these actions from the program, Yahoo! remains focused on driving user engagement with the Flickr property. As their focus shifts from Flickr PC registrations to Flickr mobile application downloads, we’ll be evolving our affiliate offer accordingly. If you are interested in possibly promoting a Flickr mobile application in the Yahoo Affiliate Program, please send an e-mail to email@example.com and include your account number (CID) in your e-mail. We will review your account and when the app is ready for affiliate promotion we will reach out to you with more details if your account is deemed appropriate.”