This page of National Software Reference Library for files (http://isc.sans.edu/tools/hashsearch.html)
The National Software Reference Library is a collection of hashes of "known" software. If you find a random file on your system, and are not sure if it is part of some software you installed, enter the hash here and see if we find it. You can search for SHA1 or MD5 hashes. Database contains over 39 mln. samples.

Virus Total online service
Virus Total is an online service that analyzes suspicious files and URLs. It is developed by Hispasec Sistemas that analyzes suspicious files and URLs enabling the identification of viruses, worms, trojans and other kinds of malicious content detected by antivirus engines and web analysis toolbars.