This is awesome. Having computed a reasonable distance function between users, you should be able to use this distance function as edge weights in a big graph.

This is awesome. Having computed a reasonable distance function between users, you should be able to use this distance function as edge weights in a big graph. Rendering this graph with a force-directed layout algorithm like Fruchtermann-Reingold might create visually appealing results by clustering related users. I've done this before on different datasets and would love to cooperate with you on it...