Mushroom GreenZero: $25 - $30

When a device is plugged in and has finished charging, it usually goes to standby mode. Unfortunately for your electric bill, it still draws a small amount of power from the outlet. The so-called “electrical energy vampire” is the bane of any environmentalist's existence. Several devices work to combat “vampire power.” But the Mushroom GreenZero  promises to give you a little more of a “kick” when it's time to charge. When plugged into a device and a power source, the Mushroom starts charging when it's tapped by hand or toe.

When the gadget is fully charged, the Mushroom will automatically shut off and go into standby mode consuming zero energy. It’s compact with a cable reel and comes in three models for USB-connected devices (tablets, cameras), embedded microUSB cable and a 30-pin model compatible with Apple devices.

For those who own several devices in need of charging, the Mushroom may not be ideal, since it only works with one device at a time. Most chargers now have “trickle mode,” this is the mode where chargers trickle a small amount of power to devices once they're full to prevent the battery from naturally losing its charge. The cost for the Mushroom per device may exceed the cost that just letting trickle mode happen.

It’s a cute plugin that would make for a good travel or work charger, but don’t expect to see it used for daily overnight charging.