Where to declare global variables?

[eluser]Mikkel Juhl[/eluser]
Hey CodeIgniters!

I just tried the CodeIgniter framework, and I'd say.. I am impressed. It's lightness, and easiness.. Only after a couple of hours, I really feel that this definitely has a future in my coding..

Anyway, I am looking for a place where I can decare global variables.. The variable I need to declare is the name of my site? How would you declare that, so I can use it everywhere in my code, without using the: $data['title']="sitetitle"; in every single function?

Cheers!