I've used these guys (UPAK): http://www.upakstorage.com/
If you've heard of PODS, the concept is similar. They drop off a container at your house/apartment/whatever. You pack it and put your own lock on it. They come pick it up and store it. When you want it again, they deliver the container wherever you want. It's not a bad way to move. I ordered a container to put in all my extra stuff in order to de-clutter and stage a house for sale. When I move to my new house, I simply had them deliver the container to the new location. There is a pick-up and drop-off fee as well a monthly storage fee. All are quite reasonable. The only thing I don't know is whether you can access your stuff when it's in storage. I didn't have to do that.