Meguiar's makes a decent plastic polish. I have a feeling that it works better using a buffer tool with it, than just trying to polish by hand. There's lots of plastic polish on the market now because of all the plastic headlight lenses on the new cars that are yellowing and clouding up..........
I'm curious to see what other methods are available too.
I use my 3" air mini buffer and started with 3M Perfect-it and wool pad then finished them off with Meguiars #3 final glaze and foam pad. Mine turned out nice except for the small age cracks.
I swear I seen someone repopping the lenses somewhere.