Can someone please tell me why, when i add content to this site, there is a huge gap between the end of the content, and the footer.

http://www.tremorchrist.net/index3.html

On the home page (linked above) theres a photo, then you'll see a big gap below that, then the footer. I'm trying to get rid of this gap, but cant seem to do it for some reason.
Pages with no content on them are ok.
Whats causing the gap? (No, theres no p or br's etc and Ive checked margins and padding as far as i can see)

I'm sure its quite a simple answer... anyone?

edit: would also LOVE if someone could tell me whats stopping this from working in mozilla