A public domain book on the history of how computers influenced early US spaceflight, and vice versa. Originally published as a public domain set of Web pages by NASA's history office; (imperfectly) converted to Kindle format by Armando Fox as a labor of love.
This if available on one of the NASA websites as HTML and a honking great big PDF.
Just something I'm dipping into, not reading cover to cover. Good fun to read some of the details of unmanned space flight (the first part of the text also covers manned space flight computers). Bonus geek points for a discussion of a couple of the NASA-specific programming languages in the appendix).