I'd have to say that gcc is the unsung hero of FOSS. If you wanted compilers on your shiny new commercial-UNIX box, you either had to fork out $$$ or find a way to get the GNU toolchain into place. Even on PCs compilers tended to cost a lot, with Borland being a shining exception.

Somewhere, I still have a Red Hat 5 retail CD. I'm not sure, but I might have bought it at Borders Books rather than a computer shop. I know I bought a few CD-ROM collections at the bookstore.