Here are some books from Packt publishing to help you get the most out of Joomla.

	Joomla! Web Security By Tom Canavan.
	Joomla! Accessibility By Joshue O'Connor
	Building Websites with Joomla! 1.5 By Hagen Graf
	Learning Joomla! 1.5 Extension Development: Creating Modules, Components, and Plugins with PHP By Joseph LeBlanc
	Joomla! Template Design: Create your own professional-quality templates with this fast, friendly guide By Tessa Blakeley Silver
	Mastering Joomla! 1.5 Extension and Framework Development By James Kennard
	Joomla! Cash By Brandon Dawson and Tom Canavan
	Building Websites with Joomla! v1.0 By Hagen Graf