OTV seems pretty cool and I can definitely see a place for a way to implement a "L2 OSPF".

My top three would be:
1: UCS-E in the ISR G2 collapsing the router/pbx/switch/server
2: Nexus 1000V and ASA 1000V for building a manageable networking and firewall layer for the VMs
3: 6500/6800 Instant Access for extending the fabric to the remote closet