Building a site with CodeIgniter

[eluser]ThomasOwens[/eluser]
[quote author="louis w" date="1215053884"]Check out Matchbox. Let's you use a HMVC pattern which allows for "modules" of your application.

http://ellislab.com/forums/viewthread/65749/[/quote]

So this extension (or whatever it's called, I'm still learning about CI, so forgive me if I use the wrong word) will make what I want to do possible. But this functionality is not available in the core CodeIgniter installation?

And on the subject of extensions, is there an extension or module repository somewhere? I didn't see one.