Free sheet music on the internet

There are lots of old music prints, handwritten scores and parts and facsimiles of old editions that are in the public domain because their copyright have expired. There are also some generous people that publish their original music scores or their arrangements and transcriptions directly online for free use. Here are some links to some of my favourite sites for music prints and manuscripts:

• IMSLP / Petrucci Music archive Comprehensive collection of music prints and manuscripts uploaded by users of the site
• Opera Scores Demo old editions of opera scores
• Werner Icking Music Archive modern prints, lots of early music, often in arrangements
• Choral Public Domain Library choral music with or without instrumental accompaniment
• Project Gutenbergs category for sheet music Mainly string quartets
• Mutopia a little bit of everything, mainly older prints
• Free sheet music from Johan Tufvesson modern urtext prints of early music
• Cantate Domino sacred music, both for choir and organ

A lot of libraries have digitised their collections lately as well:

• Danmarks Digitale Nodebilbiotek The Danish Digital music library consisting of digitised collections from the Royal Library in Copenhagen
• Europeana The EUs digital library where you can search many digital collections from different European libraries at once
• Dübensamlingen The Düben collection at Uppsala University Library, consisting of lots of 17th and 18th century music collected by the leaders of the Royal Chapel of Sweden of the time