Figuring out how to store the Cricut cartridges is tricky. For one thing, the boxes they come in are bulky and awkward - not conducive to carrying them around or even flipping through your stash quickly. So, I have been searching out solutions to this problem and here are a number of ideas people have come up with to store their cartridges in space saving ways that are easy to carry.
This first way is my favorite and the one I use. I like that it holds SO many cartridges - there is room for 40! Not that I have that many, but it's nice to have room to grow (ha ha!). Also, it's compact and simple.
Snapware Ribbon Holder for Cartridges:
HERE on this thread on the Cricut MB, Channyne posted actual instructions on how to cut that large needlepoint plastic canvas to separate the cartridges and it works like a dream in the bottom section. I also used a black Sharpie pen on the top side of my cartridges to ID them (like PDDU = Paper Doll Dress Up, etc.). You can purchase these Snapware Ribbon containers at Lowe's and Target (check Christmas clearance aisles) or online
HERE for $11.49 at the Container Store. They have a similar looking item at Joann's but don't buy that one because the bottom of the top large section has a scooped area and the books wouldn't fit in there correctly.
Other options are:
Cricut Storage Book:
Cricut sells a book that looks like the cartridge books but holds just cartridges and overlays (see above photo). This holds 8 cartridges, can be either orange or blue (so you could have fonts in one and shapes in the other) and retails for $9.99.
Scrapcessories Caddy and Tray:Caddy:

Tray:

Then, this woman on the Cricut message board has designed and is selling these (above photos). She has a caddy for $12.99 that holds 8 carts and all their accessories (booklets and overlays). Or you can just buy the tray only for $8.49, which could be put into a notebook, after punching holes with the Crop A Dile. Prices decrease as after you buy 3 (down to $10.99 per caddy). These are a preorder item and will be shipping in February. Click
HERE to get more info and pre-order.
Other People's Solutions:Crafty Cathy stores hers on the wall:

Dany's Storage Solution from Michaels:

This thread from the Cricut message board
HERE has many more ideas.
Finally, once you've come up with a storage solution, if you don't want to throw away the original boxes, you could store them inside the box the Cricut came in, because most likely you didn't throw that box out either. I know I didn't.