Wile E. Coyote's ACME catalog may have never listed a coffee grinder, but if it had, it would probably have looked a bit like this.
This is the guide to controlling a coffee grinder with a TNT blasting plunger you never knew you needed! It is admittedly pretty darned specific -- however! you can use the techniques here to use nearly any high-powered AC device as a switch for your microcontroller projects. Plus, the addition of the controllable power outlet module means you can instruct your microcontroller to turn on and off a second AC powered device, such as a blender, drill, lamp, or pump.
Besides the electronics parts listed above, you'll need a 1000uF electrolytic capacitory, and need a source of AC power that you'd like to use as a switch, such as a TNT blasting machine or hand-cranked generator.
You'll also need something that can be plugged into AC to trigger, such as a coffee grinder, blender, lamp, or pump.
A small wooden, cardboard, or plastic box to use as enclosure will be helpful, as well as a pair of #6 x 1" screws, nuts, washers, lock washers, and wing nuts to use as terminal posts.