Atheists are all over the internet, so here are a few pages which are relevant to us.

Our Facebook page, which is always up to date.
The AHS, a national group of Atheist, secular and humanist societies, of which we are members
The National Secular Society and the British Humanist Society which are nothing to do with us, but they're good groups.
The YFT is a new online Blog for atheists between 16 and 21. Feel free to check them out and 'Blog'. (Is that a verb?)