http://www.sabi.co.uk/Notes/linuxPragmaCoding.html

I thought that his page was a short and interesting read. Some tips are obvious (use header files), some less obvious (use const, static, and assert), and some are things that I really need to start doing consistently (program and version strings, get_opt_long).

Update: a long list of style guides is available at http://www.chris-lott.org/resources/cstyle/