I’ve spent a lot of time prowling second-hand bookshops looking for elusive, out-of-print titles. I’ve found some of my favorite books that way. I still remember my excitement at finding Moorcock’s Behold the Man, Brunner’s Stand on Zanzibar, and Zelazny’s Lord of Light (little did I know that some of these would eventually come back into print!). Some of these searches literally took years.
Now it looks like some of that hunting is about to get a little easier. Fellow Hopefull Monster, Terry Kidd, alerted me to an effort to get out-of-print speculative fiction novels back into print (sort of). Gollancz, an imprint of the Orion Publishing Group, is putting together a digital library that will make thousands of classic and out-of-print titles available. I haven’t seen the details yet, and I don’t know if it will actually come to anything, but I’m keeping my eye on this one because I’m stilling looking for several titles, like Asimov’s The Mule, and various New Wave titles from the 60s.
D. Thomas Minton 
I’ve just been doing this on ebay, and found that I got much of what I was looking for there.
But… it’s just not the same as pouring over shelves of cracked spines in musty old bookshops, is it?
The hunt is often better than the catch.
Colum
Yes so true: the hunt is what make the find so much sweeter. Being able to page through the book when you find it…that musty smell of age…mmmmm.
I’ve tried to find things online. One of the problem I often run into is shipping costs. Lots of the small second-hand bookshops want to charge a huge sum of money to mail book a to me. I’m not sure why considering we receive regular US postal service, and it doesn’t cost anything more than mailing it to Iowa.