http://www.dndclassics.com/browse.php?filters=0_0_44700
I think a couple years ago I was really looking for 1st edition stuff in old book stores and the like. I am glad that now I can apparently get lots of 1st edition stuff in PDF form.
I haven't been able to play table top RPGs in a long time and I'm very busy these days, but I would really like to get some 1st edition on someday. I feel like now I have the means to do it easily because I could buy the PDFs and back them up on cloud storage, so I could even do it years later. (No pesky rule changes or anything because it's 1st edition.)
With this much material, I could even start writing my own 1st edition material if I ever got a group going. This is extremely exciting for me.