" Wikia Search relaunches with features that allow users to fully edit and filter all search results, instead of the limited editing functions given to users in Wikia Search's alpha phase. Only now, Wales argues, can the real test of Wikia's community-powered approach begin". I think that the new enhanced options in Wikia Search will definitely be more useful to search the popular encyclopedia.
Read Write Web also listed recently different ways to search Wikipedia. Among them there were some like Qwika, and Wikirage, which Library Blog Buzz has covered before and others like Lexisum (short summary of Wikipedia articles) and Wiki Mind Map ( generated map on related articles) that sound quite promising.