The online casinos offer free bonus game slot machines that enable the gamblers to win real cash bonus. You have to understand that there are a number of casinos that offer this service on the internet. To know more about it you can read the blogs and reviews written by the casino's customers or check with the casino's online casinos that are associated with the slot machine business. A good online casino should be well known for providing the best casinos and bonus games. You should also read the bonus news that is provided to you by the online casinos so that you will be aware with any new update in the bonus game slot machines.