My startup office looks exactly like my living room for some strange reason. Part of it also looks exactly like the spare bedroom in my apartment. And the "break room" looks just like my kitchen. Weird, huh?
All joking aside, my spare bedroom doubles as my office/lab/library, but I do most of my work in the living room. Right now there's a gaming chair sitting in the middle of the floor, in front of the TV, and there are stacks of books off the the left, another stack of books on my right, a big pile of magazines behind that stack of books, and behind me is the dinner table, which is doubling as a repository for more books, magazines. notebooks, scraps of paper, etc. On the walls around me are a total five big whiteboards, and in the corner is one of those cheap metal & fiberboard tables, with a pile of PC hardware (some in use, some waiting to be used, and some waiting to be thrown out) on it. In the other corner is a big pile of old Sun boxes, most of which I should probably just pitch in the bin, since I'm probably never going to use them at this point. Cloud Computing, ya know? Slicehost / Linode / EC2 have kinda removed my need to keep a lot of physical hardware around.
Oh, and there are two mountain bikes and a BMX bike in another corner of the room, taking up space. That's my world these days.... computers, books, magazines and bicycles. And notebooks, lots of notebooks... I still like to brainstorm on paper a lot of times. One of those artist style notebooks (blank/unlined paper), a drafting pencil and a box of colored pencils and I'm set.