Well, when you reach a certain rank you have the possibility to add a signature under every post.
Some projects are willing to pay for to advertise them in your signature space, like I do with ChipMixer. Then you have a certain amount of posts you have to do each week in order to get paid which is logical, because the project want to have some exposure (this does not apply for ChipMixer).
You have to follow the forum
rules and not spam the forum with bullshit.
The better reputation you have the better campaigns you can join. You can check the Service section for campaigns paying in Bitcoin.
There are also bounties for the social medias. See the Bounty Section.
That sounds interesting, nice idea. Never seen such a system before.