NutchWAX ("Nutch + Web Archive eXtensions" ) searches web archive collections. The Web Archive eXtensions (WAX) include adaptation of the Nutch fetcher step to go against web archives rather than crawl the open net -- adaptation currently does Internet Archive ARC files only -- and plugins to add extra fields to the index that return an Archive Records' location in the repository, its collection name, etc.
Keotag lets users search for tags across 14 different sites, from Reddit to Ice Rocket.Keotag will also generate folksonomy tags for a blog post, or submit a bookmark to multiple sites.