A few years ago, I had the pleasure of borrowing his "mathobiography" I Want to Be a Mathematician from Steffen Lauritzen in Aalborg, and enjoyed it immensely. I plan to buy a copy for my bookshelves at some point.
Bas Luttik has keeps telling me to read Halmos's expository work on algebraic logic. I keep postponing doing so, but maybe now it is time to start. At least after some pencil sharpening has taken place :-)
Let me end with a quotation from Halmos's mathobiography I like:
"I love to do research, I want to do research, I have to do research, and I hate to sit down and begin to do research---I always try to put it off just as long as I can.
....Isn't there something I can (must?) do first? Shouldn't I sharpen my pencils perhaps?"- --Paul Halmos, I Want to be a Mathematician
These days I sharpen my pencils a lot, alas.