The Wighton Database is a pretty comprehensive index of al the books in the collection, most of them with complete lists of the titles of tunes in the books.
The old database is broken. There are plans to place it on Dundee Council servers and to expand it, but this work has not been completed yet.
In the meantime you can use this temporary online searchable version of the database made by John Bagnall:
Temporary Wighton Database
Website by Simon Chadwick