Third level navigation examples

The problem

The problem we are trying to solve is that our navigation is up to three levels deep and we don't know how many links will be in the third level.

These unknowns make it almost impossible for us to keep the navigation on the left hand side exclusively without taking away parts of the navigation. The right hand side is also not an option, as it will be used up by marketing collateral and might be easily overseen due to "banner blindness".

Therefore we agreed that we try to fit the links above the main content, and wondered what way would be the least obtrusive while being intuitive.

On the following example pages we can see several approaches to try and display these links, each has the potential problems listed.