So, I purchased a 8-relay module from here:
I would like to control wall outlets with it. Where do I connect 120v power on the relay board to power the plugs? Also, can I give each plug on a two-outlet socket it's own controlling relay? (Just for reference, the pins on the relay board are: GND, IN1, IN2, IN3, IN4, IN5, IN6, IN7, IN8, VCC, and then a smaller header with pins GND, VCC, JD-VCC, and VCC and JD-VCC are jumpered.)
Thanks 
You don't power the plugs from a relay board: you take power from the wall plug, and put the relay between that wall power and the appliance. The relay is simply an electrical version of a manual switch.
Ok, thank you. 
And while it's not the forum's job to be the "mains wiring police" it would be remiss of me not to point out that if you didn't know that, you're going to kill yourself. Or worse, you'll leave a piece of equipment wired up in such a way that it will kill someone else.
I am, as they say, "out".
You can get wirelessly controlled power outlet adapters, much more convenient that
running wiring everywhere - worth considering.