Most people here use the green background. It is the colour which Barrysworld, and now Freddyshouse, is meant to be.
I can't see a web-based IRC being made active for general use. You'd be best either hosting your own (password protect it, for your own good), or getting a client that is available with the browser, or a proper client. I assume you are trying to overcome a work/school firewall, so you can only really take the former option.
You will need your own hosting. If you have Java enabled where you are browsing, you have lots of choice. If you do not, you can either use CGI:IRC, or I have seen a PHP-based version. Look on Sourceforge for downloads.