If it's a more casual site where users hang around then satisfying self-expression needs by selling virtual goods around avatars, gifts etc. can be a possibilit

If it's a more casual site where users hang around then satisfying self-expression needs by selling virtual goods around avatars, gifts etc. can be a possibility. It has been quite successfully used by several casual gaming sites and visually intensive social sites (Habbo, Playray, Stardoll ...)