[Mediawiki-l] Writing extensions for MediaWiki

[Tech Geek]

Hi all,

I have been playing with mediawiki for past 6 months and I am getting more
and more comfortable with it and I like it a lot. Now I am thinking to start
writing extensions for mediawiki starting from very simple (Hello world
types) extensions. I am familiar with PHP and have done some LAMP based
database driven websites.

Can someone recommend a good source/pointers from where I can start learning
on how to write extensions? Also I would like to know what is the simplest
extension (based on lines of code) for mediawiki that is currently available
so that I can look at the source code and learn from it too.

Thanks