Which is the best dictionary of websites?

There is no such dictionary. We have search engines.

100 search engines: www.distancedegrees.com/2008/lose-your-wikipedia-crutch-100-places-to-go-for-good-answers-online/
Google tricks: www.johntedesco.net/blog/2012/06/21/how-to-solve-impossible-problems-daniel-russells-awesome-google-search-techniques/
Google advanced: iwastesomuchtime.com/on/?i=20501