BuddyPress Global Search is a plugin that can create a unified search facility for your entire BuddyPress site, adding all the BuddyPress components into the search if desired. It extends the functionality of the existing site search.
Plugin Review – BP Profile Search
BP Profile Search is a plugin that can integrate an advanced profile search feature into your Members Directory page that searches through all or selected profile fields.
Plugin Review – BP Search
BP Search is a BuddyPress plugin that adds a dynamic drop down lookup list to the search box on the BuddyPress Members page.