Mark, for PURCHASED .pdfs I have about 15 (which is my poll answer), but as others here mentioned, I have lots more free ones especially from the WOTC, and a few freebies from Sword & Sorcery and a few others. The total is probably 100-125 or so.
I *really, really* prefer print products. Even for the pdf stuff I like- notably including CMG and SKR Games- I would very strongly prefer print products, and would pay more for them if they were an option. Maybe I am just 'old school', but there is a visceral enjoyment to the tactile sensation of reading a real book instead of on-screen. I suppose I could just print them all out hardcopy, but that is kind of a pain, and the format is a bit clunky versus a nice perfect-bound print product. (I realize this is not exactly what you were asking, but just fyi..!)