Pyramid linking : Say you have X number of sites which want link_backs, so you create a special page on your site called 'links' it gets populated with keywords/follow links for X number of sites. In return you get X number of sites linking back.
But instead of Site A linking to Site B and Site B linking to Site A there is 3 sites taken into account for the linking strategy so that google (and others) considers them one-way links.
Site A > Site B
Site B > Site C
Site C > Site A
(edit) .. I think I referred to link triangles not pyramids