A couple of weeks ago, we shared with you the way-too-deep baseboard in our rented Montreal apartment. We decided to install a low, linear shelf along the wall the bed is on.
The shelf is made up of 3'-long segments like this. The back of the shelf rests on the baseboard and the front on paper tube legs that we scavenged from a fabric supply shop. The legs insert snugly over tin cans(!) that are screwed into the bottom of the shelf. The cans act to hold the legs in place and connect one shelf to the next.
The solution has worked well for us in this one-year rental: We didn't have to mar any of the apartment's surfaces, we can reuse the 3' long shelves when we move out, and the paper tubes and tin cans will be recycled. In the meantime, we have a bedside table, a little book storage space, and we've put that 3" deep baseboard to work.