Here is a neat little gadget for all you germ freaks and kitchen cooking lovers. Daysago is a tracking device that informs you how long your jar has been opened. It has a simple LCD and can be attached with its magnet or suction. The device is in reality a timer which keeps track of how long your jar has been open so you do not have to stick your nose in it. Since sticking noses in jars is so old-fashion! It costs $12US so perhaps if you have a few jars in your house, you are looking at a good $150.
You can use it for pretty much anything, stick it beside your plant and it will count how long it has been since the last time you it had water.