Index to the works can be found here: http://www.npj.com/bach/BG.html
Access through IMSLP:http://imslp.org/wiki/Bach-Gesellschaft_Ausgabe
Full Vocal Parts with Piano Accompaniment
They also offer an audio stream of his works: http://www.poonhill.com/audio.html
The complete works of Mendelssohn available digitally from the Bavarian State Library.
Digital reproductions of more than 500 music autographs and life documents by Franz Schubert.
Lots of opera scores.