For every Watch the Throne or What a Time to Be Alive, there are scores of joint hip hop projects borne of one epic late night in the studio that never crystallize into a fully formed release. As fans, we should know better than to let these glimmers of collaborative greatness get our hopes up. But the possibilities are too great to ignore.

This list is not comprehensive; we didn't include the rumored Big Sean and Mike Posner (lol) collaboration, for example. Click through the gallery to see 10 of the most potent unreleased projects in hip hop.