It only works once per wallet, but you can use it with differents wallets and... it gives you between
     
5 and 10 Ksat. (depending on what you do to promote their web, 5 if you don't do anything, 2 more if 
    
you tweet 2 if you post on face... and so on...)
    
It gives you a temporal wallet, but it's not important, you don't need to take a note of it or anything, at the
 end it will ask for your real wallet to pay you.
     
http://cur.lv/4xw8e
   
Another one! It gives you a good amount :)