Here's an easy way to turn a bookcase into a bed. No tools required. That's right: no drill, no hammer, no nails -- just paint.
What you'll need:
A sturdy bookcase. Ideally, this should be at least one foot longer (taller) than your mattress, so you can have a built-in bedside table. You can repurpose a bookcase you already own, or find a cheap one on Craigslist. Last time I checked, there were dozens. Or, if you're feeling really crafty, you can make one yourself. There are lots of Instructables that can show you how to make a bookcase cheaply and easily.
A can of paint. Whatever color suits your fancy.
One piece of plywood that fits over the bookcase, cut lengthwise into two planks.
Step 1: Paint your bookcase & panels
Step 4: Admire the nifty storage space
Step 6: Nifty Extras
1) Without a headboard or typical bed frame, it doesn't look like a bed, so you can easily use it as a sofa, by throwing some extra pillows along the wall.
2) The platform extends beyond the mattress, so you have a spot for books and drinks, whether you are in sofa or bed mode.
3) The storage under the bed is easy to get to. Just flip the mattress up against the wall and lift one of the platform panels. Voilá!