Which ads can I add?

You can add any ads that do not brake our Terms of Service.

As stated in our ToS under point 6:
6.1. The website must not contain pornographic, racist, discriminating, vulgar, illegal, or other adult materials of any kind.
6.2. The website must not contain any frame breakers.
6.3. The website must be English.
6.3.1. If you want to add website that is not English, you have to use proper Country Targeting.
6.4. The website must not contain or promote any viruses.
6.5. The website must not contain ANY prompts such as download dialogs or confirmation alerts.
6.6. The website must not exceed the 1 popup/pop under limit.
6.7. The website's single popup/pop under must not open any new windows.
6.8. The website's single popup/pop under must not break any of the above terms.
6.9. We reserve the right to refuse any advertisement that we consider not suitable for display.