They come and go. I earned a little money from Alladvantage, but it has stopped paying money out. They can't be a scam because it *is* something for nothing, only it isn't a lot of *something* in exchange for your screen real estate
I've used Alladvantage, Spedia and now Surfmiles. Alladvantage stopped paying and although Spedia dropped their rate per hour they do pay out and on time. The only setback is that they pay in dollars. Surfmiles however pay in � sterling although limit their hours to 7 @ 30p per hour but with a good number of referrals you could easily earn the �15 min each month to receive a cheque. It won't make you rich overnight but goes a fair way to paying the internet charges!