I met another teener owner at a car show last summer and commented on how nice his weatherstripping looked, thinking they were new. They were not new. He refurbished his old rubber with a product called Plasti-Dip, the stuff that you dip tool handles in to insulate them and provide grip.
I bought a can at HF and tried it out on a couple of gaskets and was very pleased with the results. It's brushable and black and when dry, retains good flexiblity. I also used it to fill small nicks in a bumper top and I'm thinking it'll take care of minor blemishes on interior vinyl. I don't think I've found all the uses for this stuff yet.
Tom