A to Z of C
   The non-profit free book on C/DOS/Turbo C programming with 79 chapters. It's available online to view/download.
   http://guideme.itgo.com/atozofc/

Applications Programming in ANSI C
   Third edition.View online of download for viewing later.
   http://condor.depaul.edu/~mkalin/ed3/

C Elements of Style
   Programming books,information, and columns.
   http://www.oualline.com/

C Interfaces and Implementations
   Explains the use of various interfaces such as string manipulation and data structure.
   http://www.cs.princeton.edu/software/cii/

C Programming: A Modern Approach
   A comprehensive tutorial and reference.
   http://www.knking.com/books/c/

Scholarly Resources for CompSci Undergrads - C
   C tutorials, references and links.
   http://www.csd.uwo.ca/~jamie/C/

Simulating Ecological and Evolutionary Systems in C
   Book by Will Wilson. The book starts with elementary programs modeling stochastic birth-death processes, slowly increasing programming complexity as the chapters progress.
   http://www.biology.duke.edu/wilson/Book/

The Annotated Annotated C Standard
   This is a review of the book explaining some of the errors found.
   http://www.lysator.liu.se/c/schildt.html

The C Book
   Complete online version of second edition book by Mike Banahan, Declan Brady and Mark Doran. Popular introduction to ANSI Standard C.
   http://publications.gbdirect.co.uk/c_book/

The C Programming Language
   By Brian W. Kernighan and Dennis M. Ritchie, the original (revised) and the best book to learn C.
   http://cm.bell-labs.com/cm/cs/cbook/index.html

User's Guide to the GNU C++ Class Library
   This manual documents how to install and use the GNU C++ library.
   http://sunland.gsfc.nasa.gov/info/g++/Top.html

Writing Bug-Free C Code
   Online book by Jerry Jongerius advocates a style of programming based upon classes, data abstraction, run-time type checking, and fault tolerant functions which results in bug-free C code. Sources, Amazon link for printed copy.
   http://www.duckware.com/bugfreec/