There are so many useful sites for first graders...
I have joined a few sites that I feel will enhance the concepts I am expected to teach in first grade... The list could go on forever...
ReadingA-Z.com (paid site)
Epic Book (paid site)
Children's Books by age and subject
http://www.scholastic.com/bookwizard/ (if you are looking for books that are "similar" to the ones your child enjoys)
Brainpopjr.com (paid site)