This is a site where every 30 minutes, you can win 0.007 BTC by winning the most games.
It is 100% free, so you can't lose anything.
The link is http://cur.lv/4sbha
If you prefer not to give me a little extra money, the link is http://cashclamber.com/

Of course, if it turns that you are really good at these games and you win lots of
BTC, the ethical thing to do would be to send me some :) 142gq2sC1xLzUsCb2NZA82fTsMwqa3Z5Vx