Tether is a new $0.99 jailbreak tweak from Philip Tennen and Evan Luther, and it's pretty awesome. I like this tweak, not so much for what it does, although that's handy as well, but I like it for its originality.
By using a 3D Touch gesture on the Home screen, you can invoke the Tether interface. Tether's interface consists of a clock-like glyph with a line extending from it. As you drag your finger away from the point of origin, you'll see a small time readout spell out a future time. The further your finger is away from the origination point, the further in time your tether will be.
When you release your finger, you have the option to set up an Alarm, Reminder, or Calendar event at the specific time that you selected. If it all sounds little confusing, it's because it's much easier to explain by watching it in action. With that in mind, have a look at our hands-on video walkthrough for all of the details.