I have recently used amazon.co.uks refer a friend system. This involves referring twenty of your friends and amazon will send them all a £5 gift voucher. I would get a £5 voucher for every person that registered and spent their voucher on goods from amazon. I was very excited at the prospect of free cds etc!
I soon received two £5 vouchers which I then repeatidly tried to use on the site. I was then informed I could only use one at a time and if I entered the voucher code but didnt confirm my order it was used anyway! I then e-mailed amazon about this matter and I was ignored until my thrid e-mail, then they suggested I try it agian. However I have still not managed to use my gift certificates. I was annoyed and disappointed with amazon about this as I had used them many times before and received a good service from them. So, a warning to anyone thinking of using the refer-a-friend amazon system - dont bother!
Apart from this I have had very good expereinces with amazon.co.uk, they are very quick to send out their orders, have an excellent selection of goods and have very competitive prices. so, if you are not going to use the refer-a-friend system use them they are good.