I use the 10 W iPad USB power adapter to charge an iPhone. That 10 W is maximum, not mandatory. The voltage is 5V. It's just the maximum amperage that's different. The iPad adapter is 5 volts x 2 amps, where is the iPhone is up to 1 amp.
For the Nexus 7's Asus AC adapter, it's also 10 Watts (5 V x 2 A).
BTW, unlike the iPad, the Nexus 7 will even charge over a 2.5 Watt USB port (5 V x 0.5 A), but will do so really slowly. With the iPad adapter, it should charge quickly, since it's the same specs as the Asus adapter. If I remember, maybe I'll give it a shot when I get home.
I have never seen the PlugBug. I just use the Nexus 7's included cable, as well a cable stolen from another device.