Will they be back soon?
I have contacted the administrators of Earn Free Bitcoins to inform them of this issue. I don't know how to contact the owner of the GOXKEYGEN site... It might have been hacked. Update 1, 26/02/2013: The admin of Earn Free Bitcoins says he's got a lack of advertisers at the moment, but that this will change soon. Stay tuned! Update 2, 27/02/2013: Earn Free Bitcoins works again!
Meanwhile there are a lot more sites where you can increase your bitcoin balance for free! Check these out:
(Sorry, but today was a busy day for me and I couldn't write any reviews :-P)