I thought no. But this is a big Indian entertainment site that is doing that (Notice the rectangle banner ad that floats up from the right bottom) and it moves as you scroll the page. http://www.glamsham.com/download/wallpaper/latest-wallpapers.htm How is it ok for them?
Floating a banner or content definitely increases the visibility of them. But have some limitations (which we’ll remove). In general, floating banners are used when there is no other content at their column as they are always at the "float" (position:fixed) state. This is a better & smarter solution that will float the banners when needed, re-position them and can be used in any type of banner – content combinations.