No, there is nothing (little) you can do. A contingency is meaningless because any firm would look at who they were up against and the cost and the risk would

No, there is nothing (little) you can do. A contingency is meaningless because any firm would look at who they were up against and the cost and the risk would outweigh the payoff. If you had the money and years to repeatedly sue and appeal, then maybe, some firm would take the case, eventually, as a PR stunt to champion "David" vs "Goliath." That's assuming your claim of infringement has any weight. Besides, most marketing has some logical path to it. So, if the look and feel matches up with the product in a logical way then it's reasonable they came to a similar conclusion on a parallel path, as opposed to seeing and taking your product, or borrowing liberally from it. Can you share your product and the Facebook product you think infringes?