We are avid readers. My girls would rather read a book than watch t.v. (in most cases). We have those electronic devices that other parents curse (Wii, DS, etc) but my kids so rarely play them that we don't even have to set limits. We collect books. We read them, and read them again. And we have a 2 year old who is a master shelf-clearer. These things, in combination, may frustrate some. We have a system.
One of the shelves is left empty as a re-shelving area. When it fills up, I pick a kiddo (depending on our time frame) to sort, alphabetize, and re-shelve. My oldest can do this fairly quickly, so if we're strapped for time she takes the job. However, I like it when my 8 year old (2nd grader) uses this as practice alphabetizing, sorting books by genre, etc. All of the non-fiction books are on the top of my shelf (this is basically referred to as the science & social studies section). The second row is fulllll of picture books, which are sorted by theme (holidays, animals, farm, new baby, birthday, transportation, etc). The bottom row: chapter books/junior fiction. These are alphabetized by author.
Today, Belle sorted, alphabetized and organized our books. She needs just a little direction (McCoy comes before McDonald...and then which comes first? Ellie McDonald or Megan McDonald?), which I can give while prepping lunch. It's a good situation all around, and I love knowing that my bookshelf is organized, dusted and ready for eager readers.