I found Similarsites.com today by accident when I was doing some analytical work (checking on competitors of a client). What they let you do is search for a site you like, and they return results of sites that are similar to it. It’s a great way to find competitors, or just find more blogs or sites like ones you already visit.I checked for more sites like this one, but all the other sites had very few or no results. They’re new, with Alexa tracking just going back to March, but they get about 40,000 visitors a month which is a big jump for any site so new. They’re different from the others as it looks like they have their own spider crawling to get new listings. The others seem to be just user submitted directories with virtually no results. Beware the results can be NSW if you do a search, they seem to cover all types and don’t censor results.

If you really want detailed reports on competitors, the free Seobook toolbar is great for that. It shows you the pagerank of the page you’re currently on, and also has an easy button to bring up reports with places like compete.com and Semrush to see how the competition stands in search engine ranking and even what keywords they’re buying on the pay per clicks.