The concept of the Little Free Hack Rack is similar to the Little Free Library, but more suitable for a hackerspace or the front yard of a maker.
Just like a Little Free Library the Little Free Hack Rack should be a weatherproof enclosure with a door, but it would contain miscellaneous items that could be useful to makers and hackers. You could stock it with some resistors, LEDs, capacitors, or other components. You might put your old cell phone in it, knowing someone might grab it just for the screen or the keypad. We might be able to keep old tech out of the landfill by promoting the recycling and reuse of materials.
Since we also love books, you could also put books into the Little Free Hack Rack, though you should be prepared for the books to be hacked! Someone might hollow it out to store thing in, or they might cut out the pages and use them for a decoupage project. It's all good.
For Milwaukee Makerspace our Little Free Hack Rack may be used to deal with overflow items from the Hack Rack™ found inside the space.