Have you ever seen people selling links to free xbox 360s on ebay and wandered how it actually works ?
If you have, they work in the manner of a pyramid scheme. You visit a free console website, registered with them and then click on a link to sign up for a free trial service (typically a free postal dvd rental trial service with Screenselect or something similar). One you have completed the trial, you then refer other people to sign up and complete a free trial themselves. When approx 10-12 people have completed the free trial you then get given a free xbox 360.
So whom actually pays for it ?
Well the company offering the free trial pays the referral free console company a fee, based on the assumption that a certain percentage of people will forget to cancel their free trial (or like the trial enough they want to continue to be fee paying members of the service). With all the fees generated from you and the people you have referred they have enough to pay for your xbox 360 and make a profit themselves. So its perfectly legitimate and it actually does work.
So where can I sign up and start referring people ?
One of the best and most established free console website can be found here http://www.freex360.co.uk