Wehratalbahn
This is an excellent documentation about the Wehratalbahn in Baden-Wurttemburg which was closed in 1971. Even if you can't understand German, it's worth a visit to view the unique historic photos. A feasability study to reopen this line is due to be completed by the middle of this year. http://www.wehratalbahn.de/

small forgotten lines
This is a very nice site with plenty of info on smaller lines. On the map move the mouse and click on one of the red lines. Info and links open, http://www.vergessene-bahnen.de/