The BuHa ExploitMe Contest is organized in multiple levels with increasing difficulty. In each of this levels you'll find a exploitable ANSI C program and a small advice about the kind of shellcode which should be used. The first and the second level do not require the usage of any shellcode because people which are not familar with security related bugs in C programs should be able to complete them too.
The contest started almost a week ago and until now there are 19 different participants. I was surprised about three brazilian guys which also take part in the contest and found the contest site with Google.
Check it out:
https://www.buha.info/projects/exploitme-contest/