Review for Provider for Google Calendar by Buddha001
Rated 4 out of 5 stars
All in all, this add-on is spectacular. It "provides" a bi-directional interface for Lightning to access GCal.
Apart from the mentioned issues, it doesn't seem to allow editing of a single instance of a repeating event. In fact, editing repeating events at all is a bit of a problem. Hopefully this will be taken care of in the next release...
To create your own collections, you must have a Mozilla Add-ons account.