In my bedroom: Only the one or two I have my nose in currently.
In my son’s bedroom: All the Science books.
In my daughter’s bedroom: Mostly great literature.
In my office: Most all the books we have already read that are not reference and will not read again, books I have multiple copies of that are posted to give away on Paperback Swap. These are in boxes. The books shelf is full of photo books, books I am looking forward to reading, and work related books.
In another large bedroom where someone else lives: All the history books. My husband hocked a shelf for his office but when I get another one it will contain all my homeschool reference books, the teaching books for me, all the ones referred to in the HOW Teaching Manual. It also contains my Reading Globally books. (I have challenged my self to read one book from / about every country in the world.) My geography shelfs are also in this room. I have decided to do this with my children as well and have made the list and started collecting for them as well.
In my school room: A shelf just for Wisdom literature and practical skills. Another shelf just for Bibles, and Biblical reference and studies and missions bios. There is another shelf for more literature. Another shelf for art, music and foreign language books.

I have subscribed to Library Thing to scan my incoming books and organize them under the topics in the HOW method. Then when I start a new unit, I can see what I already have, print it out and search for them, and purchase what I would like to add. I am off to pull the Oceanography resources to plan for our next unit today .

~Books to Give: books he stocks up on to give away.

~Maybe Later: books he’s given up on for now, but may come back to someday.

I have books that I have mentally noted to give away or to read later but now I am inspired to designate specific categories on my bookshelves for them. (Specific boxes is more like it, until I get new shelves, I miss my old bookshleve sigh)