I've placed the first book of a Firebird 2.0 manual on-line:
http://www.janus-software.com/fbmanual/

This book is about the stored procedure and trigger language "PSQL" and
consists of about 100 web pages. I would expect that all 8 planned
books will be online before the end of the year.

The on-line manual is user editable, in the sense that users can post
extra information, examples and corrections -- in the style of the on-
line PHP manual.

All feedback is welcome.

Enjoy!

Paul