Click on the image for a closer look.
This hack was inspired by a very small apartment and the desire to have a built-in, multitasking set of bookshelves. It contains many different pieces from IKEA (which, of course, you could always get somewhere else if you're not an IKEA fan), caulked together to create a massive home theatre unit with DVD racks, bookcases across the top, a few doors and drawers, and shelves for other decorative purposes. It's a pretty impressive endeavor for a DIY project, as it's all built-in to the apartment. Hit the link for more details. Of course, you don't have to do it exactly like this—so share your thoughts on how you would implement this in the comments.
Built-In Bookcase and Home theatre Unit [IKEA Hacker]