Graham got in before me on that one but I'll add to it as well....
Either click on 'View First Unread' or if you want to get to the last posting quickly (I do sometimes to avoid replying to something and then finding someone else has already said the same thing) just press Ctrl+End to get there instantly. From the bottom, you can of course hit Ctrl+Home to get to the top of the page. That is very useful if you are replying and want to take a quick look at the picture again. You can jump up and down without having to go back to the mouse at all.
Hope that helps
Rob