Have you thought about extending raw CSS so the user can define own styles instead of Adblock Plus appending {display:none!important;}? It could work something like domain.com##div#id{top:4px!important;}, and if a style isn't defined, revert to the default behavior of appending {display:none!important;}. Some websites layouts that are broken by blocking ads can be fixed with quick and simple rules. For example, the layout for ComedyCentral.com will be messed up if you block the ads with .doubleclick.. However, div#globalNavHolder{top:20px!important;} will fix the layout. Same goes for TheStreet.com if you use thestreet.com#div(leaderboard). Adding div#toparea{height:120px!important;} makes it nicer.
Right now, I'm using Stylish to fix sites, but having that functionality in Adblock Plus means I can push these fixes via a filter subscription instead of pulling them from every client.