Extension:TitleKey

TitleKey extension is a case-insensitive title prefix search plugin by Brion Vibber. It uses a separate table for the keys, so if it works cleanly it can be deployed without an expensive rebuild of core tables, and dumped when Wikimedia gets a nicer backend through Extension:LuceneSearch (pre 1.13) or Extension:MWSearch (1.13+).

For the average site administrator, the benefit of this extension is that it allows search suggestions (e.g. from Opensearch API) to be case-insensitive.