A Kanban board for reading.

I do a similar thing a with a spreadsheet. If you keep track of the number of entries you have in each column then you can even plot a cumulative flow diagram - seeing it plotted out helps me realize when I've got more than enough books in my "To Read" pile and that I don't need to buy any more for a bit :)

I'm imagining a goodreads clone where you can take a video of your bookshelf and generates something like this off ISBN numbers.