How to do replication of Firebird databases?

Firebird does not offer replication out-of-the-box, you need to use some 3rd party tools. Those external tools add specific triggers that log all the changes in database and replicate to other databases. Here are some tools:

IBReplicator - commercial, cross-platform, full-featured
http://www.ibphoenix.com/products/software/ibreplicator

FiBRE - open source, cross-platform
http://fibre.sourceforge.net/

FBReplicator - open source
http://www.meta.com.au

IBO Replication Module - Delphi/C++ Builder components
http://www.ibobjects.com/iborpl.html

ReplicadorBR - open source
http://sourceforge.net/projects/replicadorbr/

Replicador Firebird - freeware
Originally available from http://replicadorfirebird.ich.pro.br/
Download (2.2MB zip file) from:
http://firebirdfaq.org/files/Replicador_Firebird_1.0.12.7z

CopyCat Developer (Delphi components) and Standalone (application) - commercial
http://www.copycat.fr/

ININ Replication Manager - commercial
http://www.inin.hr/

Daffodil Replicator - commercial
http://enterprise.replicator.daffodilsw.com/index.html

DB Replicator - open source fork of Daffodil
http://dbreplicator.org/

DBRE - open source, supports Firebird and MySQL
http://dbre.sourceforge.net/

IB LogManager - not a real replicator, but helps setting up a hot-standby environment easily:
http://www.upscene.com/products/audit/iblm_main.htm

Demo Flash movie available here:
http://www.iblogmanager.com/download/demos/iblm/iblm_hotstandby.htm

SymmetricsDS - open source, cross platform, supports various DBMS:
http://www.symmetricds.org