I have AR parts and a barreled upper laying around that used to be installed on my Colt SP1 Carbine. I put the Colt back in its original configuration, now I'm thinking about picking up a receiver set and just building an AR myself. Then I'll have to decide on whether or not to keep the Colt, but I won't get rid of it until I have something better to replace it. Still, it's a Colt, and I think Colt AR's are going to be hard to come by in the future.
These are the thoughts that are bouncing around in my head - and I don't even particularly care for AR's all that much.