Frosmo works by giving you a certain amount of Frollars upon joining. You can then use these Frollars to join in tournaments for familiar (although rebranded) arcade games. if you win the tournament, you get more Frollars. Repeat forever. You can also get friends to join your team, which increases your ranking and allows you to participate together to earn mroe Frollars per day. Overall, it's an addicting service that any casual gamer should check out, especially given the integration with Facebook.
[via Inside Social Games]