I see a lot of insides of bathroom and closet doors that are full of storage possibilities.
My favorite product for a door is The Container Store's elfa door rack systems. The most popular style is a system of adjustable baskets of varying depths that snap into the vertical metal strip. They come in platinum and white. And so easy to install!
There is an infinite number of things can be stored in these baskets: meds, emergency kit, toiletries, back up supplies, spices, canned goods, baking ingredients, sports gadgets and supplies, light bulbs, pet supplies, cleaning supplies, CDs and DVDs, gloves and scarves, sunglasses, arts 'n crafts, gift wrap supplies, stuffed animals.
Sometimes The Container Store puts these door systems on sale for 25% off.
Another option is the 24-pocket shoe bag. Clear pockets are preferable so that you can see what is in each pocket.
Closet Maid also makes door rack systems.
These are all great systems for making items easily accessible and out of sight.