www.FirebirdSQL.org
This is the home of the Firebird database server. Here you can check out the latest news, events or the actual state of development. This is also the place where you can download the newest builds.

www.InterBase.com
Home of Firebirds predecessor: InterBase from Borland. Here you will find all type of informations, papers and downloads which mostly also apply to Firebird.

www.IBPhoenix.com
A company which offers professional support for Firebird and InterBase. They also sell an Firebird CD which directly supports the development of Firebird itself.
And if you are interested check out the IBPhoenix Open Source ODBC Driver.

www.InnoSetup.org
This is the home of the best(IMHO) free installation tool available for Windows.

www.wintax.nl/ISX
With this Inno Setup extension you have the possibility to add custom wizard pages to your installation. Also you get full scripting support for various conditional checks.

www.oasis-open.org
Docbook DTD's are maintained by OASIS, an independent, non-profit consortium.

http://www.docbook.org/tdg/en/html
This is online version of the Book "DocBook - The Definitive Guide" by Norman Walsh.

http://www.caldera.de/~eric/crash-course/HTML
If you are a DocBook beginner, take a look at this site. It gives you an easy introduction to DocBook.