Society in America by Harriet Martineau An interesting book about what America was like in early 19th-century. Totally free and online.
Internal Set Theory by Edward Nelson A better way of looking at infinitesimals than standard non-standard analysis. Free and online.
Electromagnetic Field Theory by Bo Thide Much better than your typical electromagnetism book. And totally free!
Demon of Longing by Gail Gilliland. I came across a short story by this (rather obscure) writer while at Michigan.The only recent writer I have encountered who writes as well as the great 19th-century writers. Perhaps someday most people will believe as I do that the twentieth-century writers who now are viewed as great are not great at all, and real literary talents such as Ms. Gilliland will be more appreciated. Not free, but inexpensive. Also available at Amazon.com (where you might find my review and my list of favorite books).
http://www.crispinsartwell.com/chapman.htm This is a bold commencement address by John Jay Chapman, stressing the importance of speaking what you believe. Perhaps it played a small role in my deciding to put my book online for free. By the way, John Jay Chapman was considered one of the leading moralists of his day, and is the second cousin of my great grandfather. So perhaps my tendency towards moral philosophizing is partly genetic. It strikes me he might just be a little bitter about his father, though. Hard to say.
Christopher Hitchens Web Christopher Hitchens is head and shoulders above any other journalist I know of. Yes, of course, I don't like his seemingly libertarian stance against regulating addictive substances, but one shouldn't be such an anti-addiction fanatic as to not see his virtues.
Spiderweb Software Fun shareware adventure games.
Abstract and Concrete Categories: The Joy of Cats I hope to read this free online book on (mathematical) category theory over the next few years. I dislike its view of foundational issues (i.e, how to get around Russell's paradox), but it seems to fit in well with Bourbaki, updating to a category theory perspective, but not just contentedly ignoring useful Bourbaki concepts like "initial structure" the way MacLane somewhat sneeringly did.