This is a question which often generates intensely heated debate!

Here's an example coding standard:
http://people.ne.mediaone.net/markodell/CCodeConv.pdf

Hitex has some documents on software quality:
http://www.hitex.co.uk/service/s...eral1.html

The 'C' Frequently Asked Questions site has a section on style:
http://www.eskimo.com/~scs/C-faq/s17.html
including reference to the Indian Hill Style Guide

I downloaded a copy of the Indian Hill Style Guide, but with comments like, "Since most of us use 300 baud terminals..." I think it may be somewhat dated! ;-)
It was in a rather strange file format, too (probably something UNIX).