The search tool I found the easiest was topix.net, because it offers a number of different search types. Whether I want to search by keywords, blog, source, URL, or even zip code, topix.net is flexible enough to allow it through Advanced Search. The one I did not like so much was technorati.com. It seemed more confusing to use than others.
I found feeds for YALSA and Young Adult Literature that I will use for the classes I teach, as well as for the classes I am taking.