The morphology and distribution of Co clusters on Au(111) can be controlled: from very small (a few atoms) randomly distributed clusters to bigger (several 100 atoms) self-organized clusters on a regular network. The substrate temperature imposed during growth turns out to be the leading parameter, deciding for spontaneous organization of adsorbed metal atoms. From a detailed variable temperature scanning tunneling microscopy (STM) study, it is suggested that this way of organizing matter at the nanoscale may be used to achieve new material properties. In particular, from in situ magnetic measurements on the example of Co on Au(111), it is shown that the direction of the magnetization can be adjusted from in-plane to out-of-plane, depending on the growth condition.