I would like to have an enclosure that plugs into household voltage and has the capability to turn outbound power on and off via command that comes in over radio (WiFi or nRF.) I would like this to be self contained. I intend to use a one of those blue relays to control the 110V line voltage. What is he best way to provide power to the AVR? The best thing I can think of is to put a wall wort into the enclosure and wire that up to power a small custom board that implements the functionality. I'm also considering running the device at 3.3V since that's the level that the RF solutions are happy with (nRF24L01, ESP8266.) One strategy would be to buy an outlet strip (that can be opened up) and remove enough outlets to provide space for the rest of the electronics.
The problem I am trying to solve is keeping a laptop battery charged. Battery life can be extended by charging between 30%-70% and the bios and drivers on my laptop do not support internal control. :( Moreover, it seems to me that this setup is generally applicable to lots of situations and I cannot be the first to want to do something like this. The Power Tail comes close but provides no provision to power the AVR.