In search of examples of malicious source code

I am currently working on a research project and designing an application specifically aimed at locating malicious logic embedded in source code (C/C++ for now, other languages will be addressed later). As a test of the future implementation I would like to use as many real life examples of code as possible. Anything that was known to have been compromised, had a backdoor, easter egg, or other forms of malicious or undesired logic would make a good test, or at least be a 'more fair' test than anything I might write myself. 

Because those malicious versions of Open Source projects are usually taken off line just as soon as the incident is discovered, I am having a difficult time in tracking down the specific examples that I am currently aware of. I therefore would like to ask if anyone out there knows of any collection/repository of malicious source code? If not, does anyone have suggestions on specific version numbers of Open Source projects (or available proprietary code) that I should be looking for across all the various Internet archives?  

Thanks in advance!

btw - Just to keep this thread even remotely on topic the answer is yes, I am well aware that you can not prove a negative. So, we don't need to go there. ;)