VirusTotal is a free virus and malware online scan service.

VirusTotal is a service that analyzes suspicious files and facilitates the quick detection of viruses, worms, trojans, and all kinds of malware detected by antivirus engines.

Specs:

• Free, independent service
• Use of multiple antivirus engines
• Real-time automatic updates of virus signatures
• Detailed results from each antivirus engine
• Real time global statistics

http://www.virustotal.com/