VirusTotal

VirusTotal is a free service that analyzes suspicious files and URLs and facilitates the quick detection of viruses, worms, trojans, and all kinds of malware.

In addition to using your locally run anti-virus, VirusTotal is good tool to scan files and websites.  Before using, read the Privacy Policy for details regarding the collection and use of submitted files, URLs and personal information.

https://virustotal.com/