For instance, I want to display a different ad on the forum index vs within forums. At the moment, I either have to modify the template to add the checks at a template level, or resort to a really ugly javascript solution. It would be helpful if instead I could use template syntax to check the request URL, and it could also be used to customise ads to users, etc.

i did ugly theme code hook just to show member ads per topic or pages record this suggestion would save me from doing it and save my time and brain from sever headache