I recently stumbled across a discussion of techniques for working with this type of data and I'm looking for a toy dataset to play with. For those unfamiliar with the terminology, a multigraph is a network where a single edge can describe multiple different kinds of relationships. Think of it like a collection of adjacency matrices whose nodes are the same but whose edges are different, so you can stack them into an NxNxK cube, where N is the number of nodes and K is the number of types of relationships.