If you've ever struggled finding guided reading resources for use in your classroom (I know I have!) then you may find readworks.org useful. It has hundreds of reading texts on it, ordered by US Grade, Lexile level, text type and skill/strategy. Each resource has a reading text, along with comprehension questions (which can be used to differentiate) and the all important answers.
The site is focused on Reception through to UK year 7, so is fabulous for all primary schools. It also includes a growing number of lesson plans too, which are useful for developing stand-alone, whole class teaching lessons.