[walexander]

Not trying to sound cute, but The Elements of Programming Style by Kernighan and Plaugher (1974). Just read this last week during a day of plane travel.

It's all PLI and Fortran, with lots of GOTO being harmful examples, but surprisingly much of it is still relevant. It's a quick read and interesting look at some of the problems they had back then (and some that we still create plenty of today).