Right. The RER does, which you can take into a metro station in Paris. I usually go to Gar Du Nord and change up there (I'm sure I spelled that station name wrong, but you can figure it out)

I've used these guys for a shuttle..

http://www.paris-blue-airport-shuttle.fr/index_en.php

They serve most of Paris. It depends on the city region, but they can help you figure it out.