A lot of people dont know that many of the every day sites you use to shop online you can earn some extra cashback on every purchase you make, it may not be much but it certainly adds up, and with other things like switching your energy provider or signing up to something like sky significant cashback offers are available. I have been using the site for a while and have accrued around £400 in cashback to date. There are also small offers such as a few pence every day for doing internet searches, I personally havent done these so my cashback isnt based on that but I have heard some people do this and have earned around £200 per year from that alone.
Either way I would reccommend joining as even if you just use it for getting a little cashback on your ebay purchases its worthwhile as the savings certainly add up, but if you wish to hunt out the best offers they are out there.