Sure, we could each export our contacts and import them into each other's accounts. But that's a one-time snapshot, growing stale from the moment it's been taken. And some of my data may be obsolete, or some of hers.
Until then, Soocial (as mentioned in the article below) sounds like a fine solution — except that I have more than 250 entries in My Contacts, and paying $60/yr just to keep them synced up seems overpriced (compared to some more critical sync/shared services we pay for).
This isn't something we should be still having to think about in 2013 ( #firstworldproblem ). C'mon, Google!
How to Sync Contacts Between Two Gmail Accounts
These days, it’s hard to get by with just one email address. If you want to sync your contacts between all your email accounts, it’s actually very easy to do with a free tool called Soocial.
Since Gmail supports multiple identities, could you just use one Gmail account to pull email from your others via IMAP and then keep only one set of contacts in your main account?
Hmmm. So we have HillFamily@gmail.com, DaveH@gmail.com, and MargieK@gmail.com. We set up HillFamily to pull in and label appropriately all the mail from DaveH and MargieK, and then we both log into it and have a single contact list kept there.
Except that doesn't work on our smartphones, if we want to e our own gmail accounts as separate individuals (e.g., on Google+) but also have that centralized Contacts list.
Ahh – I see. Whatever happened to shared contact lists in Gmail? I could swear some time in history I was able to do that.
As far as I can tell — never.
It is available as a directory service in the Google Apps version of Gmail, but for straightforward (and, yes, free) Gmail accounts, no, except through a third-party (pay) app like Soocial or Plaxo.