I have a Marx overhead crane and although it manually operates back and forth or up/down, it ends up being a static decoration for the layout, so I customized the crane with an electromagnet and added horizontal movement so that loads could be moved in or out of a waiting gondola. It works very well and adds a lot of play value as an accessory.
Also I took part of an American Flyer #715 auto unloader and added it to a 7" Marx 4 wheel frame so that it would work on my Marx layout. Lots of play value at the push of a button.
Here is a video of both in operation: