Electronics and appliances waste a lot of energy when they’re plugged in but not being used. There’s even a term for all that waste—“vampire power.” A home entertainment center in standby mode, for example, can draw as much electricity as a refrigerator.

A range of new devices offer to help you manage this problem. The latest is ThinkEco’s Modlet, a gizmo little bigger than a “wall wart”-style plug that packs enough brains to continuously monitor the energy usage of any device plugged into it. ThinkEco claims the Modlet can reduce a household’s overall energy consumption by 6 to 10 percent.

Via an interface on a desktop computer or mobile device, a homeowner can shut off Modlet-connected devices and set on-off schedules for them. The devices are controlled wirelessly through a short-range wireless standard called ZigBee that’s designed for home automation.

A Modlet communicates with a user’s computer wirelessly, through a USB dongle, doesn’t require a smart meter, and can operate independently of a computer. It will arrive in big-box stores and a major online retailer sometime in October.

Its functionality and price—$45 for a Modlet, or $50 for a Modlet and USB connector—make the Modlet a hybrid between full-on home automation and a simple timer switch.

Simpler devices already on the market, such as Belkin’s Conserve, consist of power strips and individual plugs that can be switched off manually (or put on a timer) in order to stop devices from drawing power when they don’t need it.

General Electric is rolling out a more sophisticated energy-management system, in which a device called the Nucleus acts as the hub of a home’s energy-management features. The Nucleus is a three- by four-inch computer that plugs into any wall outlet. It can connect wirelessly with a home’s smart meter (if it has one), and with compatible appliances, providing a user with the same information that utility companies receive.

As with the Modlet, Nucleas information is available on a desktop computer or a mobile device, and via the Web. But unlike the Modlet, it can also tap into the existing energy management capabilities of “smart” appliances, such as dishwashers, dryers, and other ZigBee-equipped large appliances.

GE’s technology is still in trials with consumers in a handful of states, where it’s being offered by utilities as part of “demand response” programs. These programs allow the utility to selectively reduce the power consumption of customers’ devices when the grid is under an especially heavy load.

While the target markets of GE and ThinkEco have considerable overlap, for now ThinkEco is taking a more consumer-first approach. However, its biggest impact could be in the office, says ThinkEco cofounder Mei Shibata.

“In the office, it’s nobody’s job to [think about energy use]—it’s not my job to turn off my lamp even though I should,” says Shibata.

On a device like a vending machine, which can typically be switched off on weekends and overnight, the amount of time it takes for the Modlet to pay for itself in energy savings can be as little as two months, Shibata claims. While results vary depending on how much power a device is wasting and the cost of electricity, a typical payback time for devices attached to a Modlet is nine months in the home and seven in the office.

Research suggests that most energy-management systems also result in reduced consumption by users.

“I think a lot of what we’ve come to understand is that most people don’t understand energy usage at all,” says Mike Beyerle, an engineer at GE. In the trials that GE is working through now, that means users are getting an education in an area of their everyday life that was previously invisible. “They are then much better consumers and decision-makers—they’re empowered,” says Beyerle.