I have used Quidco and have made really good money from using it, but I also use some other cashback websites (which I find to be more reliable and which also match Quidco's highest cashback value).

For people interested in making money from the gambling sites, I highly recommend you have a read at http://www.laymybet.com as you can earn thousands of pounds from making and laying bets, as well as from the cashback earned.