Review for Google Contacts by Wm Gardner
Rated 5 out of 5 stars
Works fine for me. I have my Exchange contacts uploaded to Google. Instead of local address books, I have all my Macs look at the Google contacts. So far, no problems at all (have run this way for a few weeks now).
I like this better than Apple's Address Book because Thunderbird can understand the groups/lists that are on Google. I use category codes in Outlook, these become groups on Google, I can use the groups on my Macs........life is good. No downside that I can find so far :)
To create your own collections, you must have a Mozilla Add-ons account.