Tristam Needham - Complex visual analysis. Lots of fun stuff about complex numbers. I love the way you can get the sine, cosine, and exponential functions from Euler's formula.
Roger Penrose - The road to reality. This is definitely a long-term project, so I'm taking small bites. But well worth it. Lots of stuff on complex numbers and it goes nicely with the Tristam Needham book.
Robert Zubrin - Entering space. Aerospace engineer and space-travel advocate explains the how, why, and how-much-is-it-gonna-cost of space travel.
Vladimir Chobotov - Orbital mechanics; and Howard D. Curtis - Orbital mechanics for engineers. I got these from Powell's Technical Books. An ambitious (and spendy) choice but proving well worth it. I've already worked out two simple problems (involving rocket fuel and orbit altitudes) and I'm SOOO excited! (For the orbit altitude problems you have to remember to convert from "apogee/perigee radius" to "apogee/perigee altitude" by factoring in the radius of Earth. Which I remembered to do.) The math isn't that difficult, and there are solutions given in both books, so I can do a lot of work in these without getting discouraged.
Hawking and Penrose - The nature of space and time. This one was a little too ambitious. The math and language are too technical and advanced for me; I can read a paragraph here and there for information, but I'll have to put this one off until I'm in grad school or something.
Roger Penrose - The large, the small, and the human mind. Much more accessible than the previous title, and (as far as I can tell) covering much of the same territory. What I love about Penrose is that he explains things in layperson's terms WITHOUT dumbing-down the discussion. Great discussion on probability amplitudes, plus a forum at the end with three scientists debating conceptual questions of physics.
Richard P. Feynman - Lectures on physics (CD). Yay! Richard Feynman has a new album out! Or rather, volumes 7 and 8 in the CD edition of his recorded lectures from the early 1960s. The new release covers light and mechanics. Great for audio-learning (even though you may grow weary of RPF's Brooklyn twang). I don't know whether RPF ever imagined he would achieve immortality in quite this form!