Just deleted my account, don't feel like going comcastic.

If only it would also support Entourage... A real shame that it doesn't (yet?). For the rest: fantastic product. Using it for years already.

This offers the easiest way to synchronize my Macs with Thunderbird.

@ norz: I think you have to be fair and could mention that today on Techcrunch Mr. Arrington wrote something new about Plaxo:
http://www.techcrunch.com/2007/10/05/plaxo-linkedin-iphone-brilliant/
It seems that the guys from Plaxo learnt something.

Note: Plaxo has a history of spamming: http://www.techcrunch.com/2006/03/22/plaxo-now-with-less-evil/

@sentience :
Try http://osx.iusethis.com/app/thunderbirdwithspotlightampadd

I hope they add better to-do support, and Gmail sync, and GrandCentral sync...
This link will download directly:
http://preview.plaxo.com/po3/?module=dashboard&operation=addSync&cid=Macintosh

Actually, I've changed my mind, it caused severe damage to my Outlook database and I had to repair everything by hand. I won't be using this one any more.

I use this to synchronize Address Book with Thunderbird's built-in address book, until such time as Thunderbird's Address Book integration is released. Works great!

Absolutely flawless, there’s nothing like it for simplicity. Does the equivalent of what previously required endless coding, manipulating and praying previously.

Now if only they could include Gmail contact integration....