You could buy a bunch of independent modules to sit between your appliances and the outlets they plug into. Or you could get an Ecoisme Energy Monitoring System. This intelligent box connects to a single outlet in your house and uses an easily-installed clamp to attach to your main power line, automatically recognizing the power profiles of your devices. This lets you track energy usage, get alerts when you leave devices like irons, hair curlers, or AC units on, and can even get reminders to close the fridge door. In addition, it can talk to other smart devices on your network, letting you manage them from a single app, and can let you weed out inefficient devices to help bring down your energy bills.