From an idea mentioned by Doug Gourlay (@dgourlay) at the C-Scape conference:
"How about using netflow information to re-balance servers in a data center"

Routing: Controlling the flow of network traffic to an optimal path between two nodes

Virtual-Routing or Anti-Routing: VMotioning nodes (servers) to optimize the flow of traffic on the network.

Using netflow information, identify those nodes (virtual servers) that have the highest traffic "affinity" from a volume perspective (or some other desired metric, like desired latency etc) and move (VMotion, XenMotion) the nodes around to re-balance the network. For example, bring the virtual servers exchanging the most traffic to hosts on the same switch or even to the same host to minimize traffic crossing multiple switches. Create a whole-data-center mapping of traffic flows, solve for least switch hops per flow and re-map all the servers in the data center to optimize network traffic.

There's a startup there somewhere. Route the node, not the packet.