I have hundreds.
At the beginning of the D20 explosion, I was lucky enough to immediately recognize a lot of the best publishers, and I collected their stuff obsessively. (Actually, the only reason I've stopped is that I vastly outpaced my own ability to read it ... and I read fast. They've also slowed down, but I have an entire shelf of material waiting for me to catch up to it.) I own -- or did own -- every WotC D&D book, nearly everything from Green Ronin, FFG, Penumbra, and Malhavoc, and many miscellaneous titles.