When I saw this picture I wondered why I have not thought to use slatwall before; my husband has always had some scrap pieces laying around. This could be a great use of the base of his bunk bed as well!
The stylists know best in the new IKEA catalog; as apartment therapy points out they are full of different ideas on how to make use of wall space.
Another picture from the IKEA catalog, a lot of their modular units can be combined and mounted on the wall, freeing up valuable floor space.
I have seen lots of outward facing book storage online this year; we did put one rail alongside Henry's bed but found he kicked the books off in his sleep. Perhaps putting it on another wall would be a good option.
Finally, I can't forget the use of hooks and magnets! You wouldn't believe the amount of toys that this could be useful for. What are some of your creative toy storage solutions?