This blog (by Zeev Barkan) is dedicated to the Star of David, its history, its various meanings and usages in different cultures. It includes thousands of pictures of Star of David, six-pointed stars, hexagrams, Solomon's Seals, Magen Davids and yellow badges,and served as a resource for three books and four art exhibitions.
The emblem of Hashomer Hatzair is very similar to the Star of David found on Sufa ruins, but I'm not sure the members of this youth movement know about it.
Picture of the Star of David on the emblem of Hashomer Hatzair is courtesy of Wikipedia