The Law, by Frederick Bastiat
Anti-Capitalist Mentality, by von Mises as Black Elk mentioned
How to Lie with Statistics, by Darrell Huff
Each of the above are thin little tomes that you can stick in your pocket at the beach. Actually, some of those are probably at archive.org or mises institute for free.
At some point (soon) as SoFloFreeper says, read A Conservative Mind by Kirk. Much much heavier, but it's like a fine porterhouse steak to the above M&M's.
And for sci-fi fun, read A Step Farther Out from Jerry Pournelle, and or Lucifer's Hammer. The former to see what optimism in science was once like, the latter to see how badly hollywierd gets their asteroid impact movies wrong in science and in sociology terms. Scary!
And for refresher, read Reagan's An American Life. You got nothin else to do! =)
Great recommendation on Lucifer’s Hammer. More of a TEOTWAWKI movel. I just read it earlier this year. Found it on a free online library and downloaded it. Read it in two nights.
Not sure about Conservative principles in that though, other than not depending on the government to save your a** when things get bad.
BTW, I would look for any recommended titles on http://www.onread.com. It is a free, online library that contains far more than just public domain works. It even has works just a few years old.