[daemin]

Yes, you could write such a program.

Yes modern OSes do use non-Application RAM for caching, mostly files and other small buffers. While Firefox is probably doing a lot of caching for web content, something that modern OSes don't yet do. Hence I have no qualms about it using over a gig of RAM.

I guess my comment was read more angrily than I meant it to sound. What I mean is let applications use as much RAM as they need and be done with it.