User post: How do you maximize limited space in an apartment?

I'm moving into a new apartment in three weeks, when I get married. My fiance is living in the apartment now. At the present time, most of his stuff is still in boxes (he just moved in two weeks ago). I'm occasionally moving some of my things over, but not too much.

As we combine all of our belongings, I find we are running out of space. I've still got lots of editing of my belongings to do, but we don't have much in the way of storage for all our things we don't use very often.

We have a few obstacles: books, guitars, keyboard, video games, many framed pictures, my craft supplies, etc. My big problem is the apartment we are moving into has a policy about hanging things on the wall. You can hang it, as long as it has a small nail hole.

This automatically rules out putting up shelves on the wall for any of my books or craft supplies. No shelf in the world can be held up by a small nail. This means pictures are the only thing they want you stick up on the walls.

I'd really hate to just line the wall with endless book cases and shelving units. I even have to get the managements approval for curtain rods. All the windows are naked at the moment which doesn't help with the monstrous heat.

What are some good suggestions for maximizing space for all our belongings? What organizational things could I do that still make the space functional, yet warm and like a home?