While we argue over at wikitech-l about how best to manage the bad image list in future, I thought it might be prudent to go ahead and write a decent extension for it, using the database, and supporting caching and all sorts of performance niceties.
This works with MediaWiki 1.7 and above and is available from Subversion. Take a look at http://www.mediawiki.org/wiki/Bad_Image_List for information on downloading it, installing it and using the damn thing.
Background: MediaWiki's "bad image list" allows trusted users to name images which won't ever be allowed to be rendered inline or in categories, etc. The built-in stuff sucks however, and is a real performance bitch when it's got a lot of items on it.
Rob Church