D.I.Y. Stirbar Retriever
To a 3/8" outer diameter polyethylene tubing a piece of copper pipe and several small cylindrical neodymium magnets are added. In such a way that the one end of the copper pipe is bent shut and the magnets cannot go into it. The polyethylene tubing is melted shut on one end with a lighter and some pressure. This wedges the magnets between the tubing and the pipe.
click on the image thumb-nails to view the photo-graph
Is this really worth a page unto itself? I think so. Many other renditions can be done using different tubing, magnets, and shafts to hold the magnets in place. This is what I had laying around. It's definitely useful, cost next to nothing, and functions as intended. If you choose to use polyethylene tubing as well be aware of incompatable chemicals with the tubing.
Idea from Magpie at Sciencemadness.