Recently I have had a renewed interest in electronics and have read several books on the subject. I have several projects at various stages of completion:
To measure the depth of water in our rainwater tank I have looked at numerous methods. The current system uses a design I developed with the technical genius of Ken Sheridan. It uses very few components for the actual level measuring, instead relying on the wonders of the PIC family of microcomputers.
Not really electronics, but people have trouble finding it, so here's another link. This is code to download the data from our PL60 solar charge controller.
There are some thoughts on the home automation project. Our house has a fully automatic heating system, with partial zoning in place, and a fully automatic watering system for my zillions of plants.
recently it has been possible to buy tiny computers that run linux and run on a whiff of electricity. I have been using the norhtec JRSX with a special kernel.