3's offer of a free sim is back - but this time, once you put your free 3 sim into any unlocked 3g phone with a simple free download you can start making free skype-skype calls over their network - without even topping up! Be quick, this offer proberbly won't last long as the last one didn't.
Usual Sim Card Price - £1.99
Edit - PLUS!!! If you keep your number - you get £10 free credit!