Not affiliated with them, just looking for some HN feedback. To be honest I was surprised this didn't come up on hnews before - or at least my googling wasn't turning up anything. There's also secretsync which I believe is the precursor to this.
One piece of advice to all using standing desk setups. Make sure your display is at or slightly below eye level and keyboard/mouse at elbow level. This makes a huge difference - particularly not having to stare down at a screen which puts undue strain on the neck.
And while you're at it - get rid of that useless caps lock key and remap it to a control key - lot more ergonomically friendly.