AVCaesar is a malware analysis engine and repository. Your suspicious files can be analysed by a set of antivirus.
A forum for reverse engineering, OS internals and malware analysis
A free Malware repository providing researchers access to samples, malicious feeds, and Yara results.
VirusShare.com is a repository of malware samples to provide security researchers, incident responders, forensic analysts, and the morbidly curious access to samples of live malicious code.