I have always organized my children's books by subject. I did it with my own home collection and I did it for two of the different childcare centers I have worked at. My categories were VERY specific, I had well over twenty or thirty different subjects for each of those three collections.
I'm not sure how I originally heard about the METIS system out in New York, but I started following the librarians who have worked on METIS about a year ago. I started to dream about reorganizing my own library into a more user friendly structure. Their organization made a lot of sense, and I liked how they incorporated non-fiction picture books in with fiction picture books to put everything in one easy access location.
In the past few months I have run across a few other systems that have been implemented in other libraries. One of the first systems I found was developed by Amy Koester at the Show Me Librarian. She called her's Picture Book City and color coded her books and used phrases for groups rather than using letters like METIS did. I loved this idea, yes colors are limiting, but I think that with my small collection, I won't have to go to a deeper level like the METIS team did and I can avoid using letters which is another representation system to learn.
I found the second system just recently in the past few weeks at Storytime Katie. She also chose to name her's Picture Book City and used colors to divide up her sections as well.
As I got closer to finalizing plans to begin this project, I ran across Gretchen Caserotti's slideshare slides for the reorganization she did at the Darien Library. Her slides were SUPER helpful in cementing my plans.
After a few conversations with the cataloger, director and outside eye I had my basics outlined and started to order the supplies I would need.