We all shop. We have to buy food, clothes, furniture, electronics - all the things that make life a bit more comfortable and all of the things that make life sustainable. So tell the world about what you have bought and where.
Others out there are going to make similar purchases and many of them want to know what to expect before they reach the store. Is the product good? Does it do what it is supposed to do? Does the manufacturer back it up? What about the store or web-site where you made the purchase? Was the service good? Was the store clean? Could the staff answer your questions?
If you are looking to make money with your blog, then this type of blog may be the blog for you. There are lots of companies out there looking for an honest opinion about their products and services. If you can demonstrate an aptitude for these kinds of reviews then this could be a blog for you.