Yahoo, Amazon web services, Godaddy, Flickr, Netflix http://mashable.com/2014/04/09/heartbleed-bug-websites-affected/
About 97% percent of the websites that are online and use SSL. Most of the big websites are affected.
There's an article on Mashable dated April 9th, 2014. It has a listing of some of the sites that were/were not affected. Also, I noticed that LinkedIn and Paypal provided updates saying they were not affected. Beware if the site is not that well-known though. Even for legitimate sites with less traffic, it can cause a problem if they don't have a scanner on their site indicating they've been infected by malware. This happens even on sites that have good intentions and no desire to harm innocent people.