Google Adsense
It would be nice to offer a bit of an interface for advertising. (in my instance, we use adsense)
Honestly, this would be a low priority, I used the menu to put the adsense ad in and that's fine. the only thing that might be nice is if it hid the ad from admins, to avoid them hitting it all the time. On the whole though, the idea of easy insertion of ads is appealing. As is, I suppose they could be built into the skins or as i did, in the navigation boxes.