The only tool I could find so far is eLibrary (
http://openelibrary.org/). But it has many problems:
- It doesn't seem to be maintained any more. And the latest source code on the development branch doesn't even compile in Visual Studio 2012 (it may compile with an older version, I haven't checked it).
- The user interface is not intuitive at all: it has many useless steps when importing data from the web (Google Books); you have to click through all the books when importing a folder so importing folders with many files is very difficult.
- Some of the tool-tips are missing and some of them are wrong. This makes the UI even more confusing.
It looks like the developer put quite some effort into this project, but didn't have time to clean things up. Perhaps it may be useful for very small libraries. I'll keep looking for alternatives...