Website to get weeding advice on particular books or subject areas.

“We do not recommend that students use the levels of a gradient to choose books for independent reading. The levels should be very unobtrusive (if not totally invisible) in your classroom. Students need to learn how to choose books based on their own assessment of readability, interesting topics or plots, favorite authors, and general appeal. You can teach students how to assess the appropriateness of texts they find interesting for their present reading levels.”  

-Fountas and Pinnell, Teaching for Comprehending and Fluency, page 152.