Here's a quick one that I've been refining a little bit lately. Every bike nerd has got a set of old steel drop bars kicking around somewhere. They are somewhat useless as a thing to bolt on to a bicycle but can be useful for a number of other tasks. Their hook shape makes them great for hanging things. Here's a set at work in my shed simply fixed to a flat surface by way of a stem face plate. I also have various other sets working as coat racks, hat hooks and to hang other tools.
Further to this they can be mildly modified to become a bike storage hook. It's a particularly satisfying modification as a set of bars can be cut in such a way as to produce four hooks. Here's a couple of pics of some lovely shiny ones I made the other day.
