I didn't see anything in the terms and conditions regarding what countries this is available to but I remember it asking me for Zip/post code so I guess it's available to at least UK and US.
A forum on exceem discusses how this is one of if not the best freebie sites in the UK and gives examples of items people have received.
This is how I did it (UK):
STEP 1 - Register
Click here for the website. Follow the instructions for sign-up. (You can change your gift after you sign up, there are more choices available)
STEP 2 - Complete ONE online offer
Advertisers pay commission for this and that enables the referral site to fund the cost of your free gift. I chose the LOVEFiLM's dvd rental trial (UK) as this is free. Other offers are low cost.
STEP 3 - Refer friends to do the same
For your free gift, get a few friends to particpate as well. Give them your referral link available once you register and spread the word around!
Final Step - Sit back and look forward to your gift!