You can only get a 30-day .mac trial account, anything else and money is involved - it used to be worth it, but you can now get an AIM account instead, and just connect iChat to that. Get an iSight too, YKYWT ;)
(Well, actually it works with ordinary webcams too with some hack or other)

I shall certainly get in touch when next in Cambridge - and bring my big... torch to find where the other end of the speedo cable goes. :)