Around (Popularity: )
http://www.around.co.uk Free membership-based service for people looking for lost friends and relatives in the UK. Includes links to useful resources.
Unidentified Persons (Popularity: )
http://meyahna.tripod.com Features a brief listing of unidentified persons with photos and descriptions. Links to additional missing persons included.
Reunite (Popularity: )
http://www.reunite.org/ UK based charity specialising in international parental child abduction. Includes online advice, prevention guides and information on support services.