Cash Back–Smart shopping

Just discovered this, so here is what I know at this point (probably going to update this post later with additional info).
If I’m wrong about something, whoever reads this, please feel free to provide more information in comments.
The cash back sites are probably getting some revenue for referring customers to specific vendors. Some of that revenue they share with the customers.
The main thing to remember is that in order to be eligible for any refund, I need to pass through the cash back web and not go directly to the vendor site. This probably means that can get a refund only from a single cash back site, even if signed up with several ones which have contract with a specific vendor.
Currently known cash back sites:
Ebates – Should be good for ebay, amazon.com purchases.
Extrabux – Should be good for AliExpress, amazon.com
BeFrugal – Should be good for AliExpress, amazon.com
PouringPounds – for British vendors
Following the signup, there is usually a need to confirm the email address and to set cash back checks postal address. As an alternative, which is great for non US users like me, there is an option to get the cash back to paypal account.
Now, all that is left is to wait for the Black Friday

* Disclaimer – the links to cash back sites contain my referral code, which means that I’ll get some refund for referral. In most of the cases, it will also generate some for the person who signs.