A simple yet elegant shelf bracket, capable of holding pretty significant weight.
I loaded it with about 50 lbs and it seemed to hold fine, using a couple of #6 x 2 in. wood screws into the studs in the wall. You'll also need a long screwdriver to access the screws through the holes in the bracket.
For the shelf part, I just bought an oak plank at Lowes and lightly sanded it.
I actually made this for a shelf so my cat could sit by the window.