As Boeing and Northrop/EADS battle it out for the contract for the Air Force's next generation of Tankers, other folks are quietly tinkering with new ideas that might make manned Tanker craft a thing of the past.
Here is the first UAV to UAV refuelling that I'm aware of. Pretty cool. Read more here on the AWS&T Ares blog-
I'm still waiting for the first UAV to UAV combat engagement.
There are two UAV to Manned Aircraft combat situations that I'm aware of. One a Russian MIG shooting down a Georgian UAV, and the other an Iraqi MIG 25 shooting down a predator drone I think in '03. The UAV tried to launch a Hellfire at the MiG, but I think the UAV got splashed first. In both instances the UAV's were designed for RECON and long loiter times, not Air combat.
In the post Vietnam area they did some experiments with UAV vs Manned Fighter combat in testing. I guess the UAV's used were target drones. From what I've heard the UAV's generally came out victorious.