iD have added their back-catalogue to steam! Also Raven have added some of their iD-engine-powered games like Hexen.

just look at the front page

I’d still rather be able to buy these titles on a CD-compilation, but I’m old-fashioned like that. This is a good move on iD’s part, and I only hope other companies follow suit!

I don’t know, however, if the various source ports like jDoom will work with these Steam versions.