First of all, thanks for everybody. Calibre is very powerful.
I don't have any idea of phyton, I tried to understand the code of a plugin for use in another and it is too difficult for me .
I "need" a Metadata Source Plugin thats search in
http://www.compartelibros.com/ is a very big database in spanish. With old and new books, the registered users can make new records and the database is growing everyday. Today 130000 books.
Thanks