Literally click a button to earn a little bit of bitcoin! Prizes range from 0.2cents (99% of the time) to 200USD (1 in 10000 chance). You can also earn interest on bitcoins stored on the site and use your bitcoins to gamble (do not recommend tbh).
There is also a weekly lottery that you get tickets for automatically by clicking on the button, chances to win are low but last week's winner won over 2 bitcoins and only had 10 tickets (5 button clicks).
Here is a link to get started! https://freebitco.in/?r=7664203
