Unobtrusive banner for multiple sites?

Question

PHP

Colleagues, the company has about 10 sites that work on various CMS (self-written and public).
It is necessary to come up with a solution for all sites - a banner scroller (apparently, some kind of pop-up, because there is no place to allocate to one degree or another).
I would like to hear suggestions on how to do this in the most unobtrusive and non-irritating way.
Recommendations are accepted, as well as ready-made examples ;-)
Thank you!

Answer 1

Go to LJ and look at the bottom of the screen

Answer 2

It seems to me that the only thing that can be done is to add an ad block in each CMS. Look at the 2KOM ad on Habré on the right (shown if a post is open, not a question).
If you do not allocate space inside the page, then you will have to allocate an entire strip above/below/left/right of the page, or make ads always hanging on top of the page. All of these options are quite intrusive if you use an image rather than text.
Although there is another option: advertising, similar to the one that Yandex shows on the sites "*.narod.ru".