Amazon offers Prime members the TP-Link WiFi Smart Plug for $19.99 with free shipping. (Best Buy, Newegg, and several other stores charge the same.) That's a buck under our mention from last May and the lowest price we've seen in over a year. (It's the best price we could find now by $2.)

It can be controlled via a smartphone and features scheduled on/off and away modes, 802.11n wireless, and voice control via the Amazon Echo.