Tikitu brought my attention back to this neat del.icio.us feature: just tag a link with for:username (e.g. for:justl0l ;-)) if you want to recommend a link to a del.icio.us user. That user can than go to http://del.icio.us/for/thatuser and see the links recommended to him/her. (S)he can even get a personalized rss feed from it. Use it!