PriceBlink. It was described to me as a money saving shopping browser add-on and that's not wrong. I did a little search and found what is barely a review from CNet, but I find them fairly trustworthy so had a look (Priceblink Review from CNet). Not really getting too much from the review, but certainly nothing really negative, I decided to install the add-on for Google Chrome, my preferred browser, but it's available for Firefox and possibly others.
So installed and forgotten about... Then a few days later, when looking for some books, a find that a little bar is appearing at the top of my browser window. Further investigation triggers the memory that I installed PriceBlink and this is it working away in the background.
What it had actually done and does is as follows. It sees the web page you are looking at and decides if it's related to a product. If it is, it will use its own sources to find out if it can find the product cheaper anywhere else. I think a few times since I've been using it, it's suggested the site I'm on, so I must have already found the best price. If it's a product that only this vendor sells, PriceBlink has also offered links to coupon vouchers.
I thought this add-on was worth sharing as it's not intrusive, not too random and has potential to make savings.