User:Enterprisey/link-deleted-revs
On error pages for deleted revisions, show a link to the Special:Undelete page. For example, this revision was deleted, but visiting that page with this script running will add a link to Special:Undelete with the appropriate timestamp.
Caution! If there are multiple revisions in the same second, this script (and MediaWiki) can only show the first one. Such is life.
Note: This script is useless for those without permission to view Special:Undelete, so if you're not an admin you probably don't want to install this.