Bookshelf woes

I am in desperate need of a bookshelf. I already have one, of course, two actually, now that I think about it, but they are on the full side. And considering I CAN'T STOP buying books, this has become a real problem.

I've been keeping a wary eye as I make my yard sale rounds and Miss J has kindly offered me an old bookshelf of hers. But this has brought up another problem: I have no room for a bookshelf in my room. The ceiling in my room slopes in at various angles, number one, limiting my spots for pieces of furniture. Number two, most of my furniture is already up against the available wall space, leaving the center of my room free for movement and activity (or more often, the piling of dirty clothes).

I should probably break down and just buy a bookcase at IKEA or something, because come fall who knows if I'll still be in this apartment or what. But then, I saw this, and I have totally fallen in love with idea of building myself a bookcase like this.

Needed: Someone with a table saw and miter saw that will cut the wood for me. Also needed: someone who will lend me their nail gun. The rest I will do myself.

EDIT: I heart Instructables. Now I want to make this too, just for kicks.