Review for gContactSync by Clemens
Rated 5 out of 5 stars
The first one for syncing Google contacts that works for me after disappointing results with "Google Contacts" and "Zindus". I haven't tried everything yet.
Multiple dialogs for master password can be avoided with add-on "Startupmaster" - also useful for Firefox.
To create your own collections, you must have a Mozilla Add-ons account.