I was introduced to Olve Maudal by a friend who used work in a company called Tandberg (which finally got acquired by Cisco). This guy is a real expert, one who can explain things nicely as well. I just finished watching his talk at this year's NDC. It is titled 'Insecure coding in C and C++'. I think it is a must watch for all C programmers. The concept of 'Return-Oriented Programming' just blew me away.
Insecure coding in C and C++ from NDC Conferences on Vimeo.