DocFetcher - DocFetcher is a portable German/English open source desktop search application.
Yojimbo - Yojimbo makes keeping all the small (or even large) bits of information that pour in every day...
SearchMyFiles - Alternative to the standard Search For Files And Folders module of Windows. Duplicates search is also supported.
HoudahSpot - Advanced File Search Utility for Mac OS X
SMF – Search my Files - SMF - Search my Files v13 is the fastest duplicate files finder and a multi-dimensional - file searcher, - file copier / mover, - file deleter / eraser, - and
DEVONthink - DEVONtechnologies develops DEVONthink, DEVONagent, and other Mac and iOS apps for document and information management and web research.