Also, for anybody doing modern C work, I strongly recommend both Hanson's _C Interfaces and Implementations_ and Ierusalimschy's _Programming in Lua_, 2nd ed. The former nails writing good C libraries, and the latter covers one particular library that provides a portable, C-friendly, mature, efficient (http://luajit.org/), ready-made scripting language that is a cleaner incarnation of JavaScript's "good parts".
Also, both are good reading. The former is a shining example of literate programming, and the latter is IMHO one of the best programming texts that wasn't co-written by Brian Kernighan. :)