I finally put together a "double singlespeed" (aka: Dinglespeed) setup.
Two chainrings, two cogs, each two teeth apart. No derailleurs, no shifters, no cables.
The two tooth difference in the front and rear allows me to use the same length chain for both gears, I just have to shift it manually. Nice to have a go fast option for when the roads are clear or an easy peddling option for when things are snowy or the trails are steep.
For those who care it's a 32x21 and 34x19 combo.
Go ask Sheldon if you care about the gain ratios/gear inches. I'm not going to bore everyone else with that here.
You get the idea.