I bounce through books depending on mood, so I usually have a few with scraps of paper lying around... let's see what's in arm's reach...
Currently reading for fun:
Machiavelli's The Prince
Neil Gaiman's book of short stories, "Smoke and Mirrors"
The Monster Book of Zombies, an anthology of zombie stories (if you couldn't figure it out)
Current philosophical readings:
Thus Spoke Zarathustra, Nietzsche
Tao Te Ching, Lao Tzu
Leviathan, Thomas Hobbes
RPG related:
Every Shadowrun rulebook
My notes for the upcoming session of my shadowrun campaign
Amethyst Fondations, Goodman Games, DnD 4e
Hunter: The Vigil, White Wolf, nWOD
Recent good books I'd recommend:
The Grand Design, Stephen Hawking & Leonard Mlodinow
The Diamond Age, Neal Stephenson
Candide, Voltaire
Once I've finished off some of the "fun" reading, I figure on digging into some more sci-fi novels & Dante's The Divine Comedy.