Normally we wouldn't necessarily promote the use of a gadget for something you could easily do yourself with minimal effort. But we've noted that friends and acquaintances often mention their horrible ability to maintain house plants due to a misunderstanding of how to care for them (either over or underwatering them). So for those flora Dr. Kevorkians out there, there's the option of a fully automated and self-sensing system so you can end your history of flora-cide...
A built-in computer automatically monitors the moisture levels in your plant’s soil, providing H20 when readings come up dry. The potter can be used with a variety of plants with their own specific soil and water needs, with a data storage option so watering calibration matches your plants requirements. Every 30 minutes the planter will check the moisture level in your pot against the original moisture level. If the soil is dry, a small amount (1/2-1/3 cup) of water is added automatically. Not bad for $49.95 considering it will likely save you money in the long run if you're already bound to kill anything leafy and alive near you.
No doubt some of you out there are wondering if you can hack this for your own personal use with one of those hat-soda can sipper cups.
Other self watering planters:
Best Self Watering Solutions for Container Gardens
Grobal Self-Watering Planter by Treg Bradley and Karim Rashid
Self-Watering Pots for Your Herbs