Around the first of the year I changed the way I store my unmounted stamps thanks to a friend that gave me a little push with some supplies for Christmas to get me started. I had all my unmounted stamps in yellow envelopes much like how some of the vendors at stamp convention display their unmounted stamps for sale. I had stamped the images on the outside of the envelope and kept them by groups.
Well I changed all that. I have now went to CD Case storage. I have the standard size CD cases as well as the DVD size cases. This was big under taking because I have A LOT of unmounted stamps.
I cut cardstock out for indexes and stamps each image on there that would fit in the case. I backed them with laminate so the stamps could stick on there because I used both back and fronts of the insides of the cases. I don't use any foam on my stamps. I used Tombow mono adhesive. Once you apply this to the back of the stamps you let it dry and it become removable. Works great.
Here are some pictures of my unmounted stamp area and the CD cases with the stamps in them.