Countdown Timer

Simply click on the icon on your addons taskbar, enter a date, and watch as the extension counts down until the start of that day.
After installing, find the extension icon under the puzzle piece in the top right corner of Chrome and click on the extension. From there, enter any date of your choosing and the extension will count down until that date, displaying the proportion of time that has passed between the countdown starting and the target date.
You can add as many dates as you want and choose between all of them. Timers are deleted one hour after they finish to reduce clutter.

Note that when there are no timers, the extensions defaults to counting down until the next year. This is not a bug. It will also clear any timers that are dates in the past automatically, as counting down to a date that has already happened does not make sense.