Another good read (it probably does not reflect how you want to write C code, the rule about dynammic allocation is probably extreme if you are not writing code to fly spaceships, but I think it is good to read regardless): http://lars-lab.jpl.nasa.gov/JPL_Coding_Standard_C.pdf
http://www.amazon.com/The-CERT-Secure-Coding-Standard/dp/032...
Online:
https://www.securecoding.cert.org/confluence/display/seccode...
Others:
http://www.amazon.com/Secure-Coding-Edition-Software-Enginee...
http://www.amazon.com/Style-Guidelines-Programming-Professio...
http://www.amazon.com/C-Traps-Pitfalls-Andrew-Koenig/dp/0201...