The Internationale Stiftung Mozarteumn, in cooperation with the Packard Humanities Institute, has unleashed a wealth of Mozart’s compositions, free, to all who would like them. As a matter of fact, they released every singe one!
The entire purpose of the web site is to “make Wolfgang Amadeus Mozart’s musical compositions widely and conveniently accessible to the public, for personal study and for educational and classroom use.”
The database repository is very well organized and easily searchable. The engine is also translated into English. The English version of the massive search engine may be found after consenting to their limited license agreement here: http://nma.redhost24-001.com/mambo/index.php
In addition to the entirety of the musical texts and compositions that may found, there are over 8,000 related commentaries and informational briefs.
This site will quickly become a much used reference for the casual and serious musician as it becomes better known and publicized. Hopefully, it will remain free and able to handle the mass traffic that will no doubt be heading its way!