Books? Amazon.
Everything else? I just Google it.<p>Yes, I know there's a bunch of opinion/review sites out there but they all suck and are fairly biased due to spam.<p>A big issue is that most of the products on specialized review sites are highly polarized... either highly negative or highly positive. Dissatisfied people, overwhelingly, seem to have enough incentive to go and review (negatively) a product. Most of the people who are satisfied are content with that and don't feel the need to waste their time and review. On the other end, highly elated people are inclined to review positively a product. So in the end, most of these voluntary review sites suck. The only reviews I trust almost completely are Consumer Reports reviews. They are impeccable and free of bias.
The real question is which sites best hide the fact that they exist to splatter affiliate links all over the place.<p>While searching for hosting last year, it took me hours before I figured out that all the hosting review sites were affiliate farms. Forums too, just look at the number of people offering up $97 off dreamhost hosting plans. At a $100 per sale I can't blame them for trying.
Usually I'll just Google the product name and follow links. If the planned purchase is big enough, I'll lurk enthusiast/specific forums until I get the information I need.