Shows the time remaining in the current Ingress checkpoint and septicycle, and the times of upcoming checkpoints.
Version 0.4 update: Informs the user about my new extension called Reference for Ingress that supersedes this one. You can get it here: https://chrome.google.com/webstore/detail/reference-for-ingress/mkkjeehbjghbhjnfekacndokjpinnhgk
Doesn't this violate the Ingress Terms of Service?
No. This extension does not contact any servers or interact with any external web pages to perform its function. It is 100% compliant with the Ingress ToS.
How does it work, then?
It computes the difference between the current time and the start time of a known past septicycle. (May 12, 2014 2:00:00 UTC, if you must know.) This depends entirely on your own system clock and not Niantic servers. (This also means that it will only be as accurate as your system clock.)
What about time zones?
Checkpoints occur in all cells on the planet simultaneously, so your time zone makes no difference in the computation. Times are displayed in the time zone dictated by your system settings.