I did until a few weeks ago. I had two spare PSUs, old mice, loads of cables, a 56k modem, and other PC junk cluttering up the bottom of my wardrobe. I slung most of it out. I didn't even know what some of the cables were for.
I've kept my old GPU (6800GT) as a back-up, my old hard drive, and put all manuals and discs in one location, but that's about all the spares I've kept.
My old Amiga went to the tip quite recently, too. I was never going to use it again, and I can't be bothered with relics any more.