I already know about SocialMedia and Cubics. Are there any other Facebook ad networks?
Sure are! Among many others (which are just a Google search away), take a look at:
It’s always worth experimenting with different ways of attracting users, but make sure it’s not detrimental (e.g., if it’s a really annoying experience, you’ll attract the wrong kinds of users or scare the right kind off) and that the cost you’re paying is worth it compared to other platforms that fit in the same budget.