This blog, started by two New York moms, reviews many children's books. They are searchable by title, author, reading level, and more. Their rating system is a bit different than many other (such as levels of humor)
Created for students reading at an advanced level who may not be ready for the mature content that sometimes occurs in books for grade levels higher than their own. Rec'd by Casey O'Leary
Readings with free activities that are lexile-leveled. It is designed for grades K-6, but there are many readings with lexiles scores of 800-1020. Also, it provides lesson plans aligned with various children's books.
You can create a free account. Rec by Karen Ault
Actively Learn lets you use their vast library of resources, at different levels, use their questions, insert your own, have it grade it for you, allow you to comment, and more.
Daily news site includes same articles written at different lexile levels, various teacher tools. Also has science. Designed for CCSS and close reading.
Website from Southern California Cooperative that lets you search for books in Spanish, books in English about Latinos, search by levels, for bilingual books, and more.