Few business resources are as valuable as your list of contacts. It's no wonder companies such as Twitter and iPad app vendor Path are--with or without their express permission.
Contacts are like rabbits: they tend to multiply whenever they get together.
In the past year my Gmail contact list has grown by 50 percent, not to mention the many updates and changes to existing entries. Contact-sync programs promise to keep the information in multiple address books up-to-date, but the programs I've tried create so many duplicate records they're more trouble than they're worth.
You can save time in the long run by doing manual touch-ups to a single master contact list and then export the up-to-date address book to your other devices. Start by cleaning up contacts in Gmail or Outlook before you import the list to your iPad, iPhone, or online address book.
Remove duplicates, refresh outdated contacts in Gmail and Outlook
The Microsoft Office support site describes your options for handling duplicate records when you import contact lists to Outlook. Once the duplicates are in the list, you have to delete them manually by sorting them by name, e-mail address, or other field, Ctrl-selecting the dupes, and pressing Delete.
Gmail automates duplicate-contact removal. Click More in the Contacts window and choose Find & merge duplicates. A window pops up listing the duplicates. Click the Merge button to have Gmail combine the information in the duplicates into single entries for each name or e-mail address. Depending on the number and content of the contacts, the resulting records may repeat the same information in multiple fields.
When I ran Gmail's duplicate-entry remover, my contact list was cut in half to 625 entries. It took about a half-hour to manually delete the remaining duplicates and remove orphan entries. The list then hovered around 600 addresses. I spent another 30 minutes updating the information with new and changed phone numbers and addresses from my iPhone, which is where most changes are recorded first.
Lastly, click More > Export, select the group you want to export in the drop-down list at the top of the window, choose one of the three export formats (Google, Outlook, or VCard for Apple address books and other apps), and click Export.
As I mentioned above, Outlook lacks an automatic way to delete duplicate records, although add-ons such as the free Outlook Duplicate Items Remover promise to do the job. (I wrote about ODIR in a post from June 2008.)
You'll probably spend more time and effort downloading and installing an add-on than you would simply deleting the duplicate Outlook contacts manually using the sort-and-Ctrl-click method. Then update the contacts with the new entries and changed information from your phone or wherever you record new numbers and addresses as you learn of them.
To export Outlook's contacts, click File > Import and Export, and step through the wizard, as described on the Microsoft support site.
Move your new contact list to an iPhone or iPad via iTunes
To add contacts exported from Outlook or Gmail to an iPhone or iPad, connect the device to a PC or Mac, open iTunes, choose the device in the left pane, and click the Info tab. The options under Sync Address Book Contacts let you sync some or all contacts with Google or Yahoo. Under Advanced at the bottom of the screen is an option to replace the contacts on the device with the list from the computer.
Replacing the iPhone/iPad contacts with the clean version on the PC or Mac avoids the duplicates that ultimately result from synching the different lists--at least most of the dupes. In testing this feature I found that there were always one or two more records on the iPad or iPhone than there are in the original list.
If you have an iCloud account you can set the iPhone or iPad to sync contacts with that services via the device's Settings options. Choose Mail, Contacts, Calendars and select Add Account. Choose iCloud, enter the account information, and step through the sign-up wizard. Select the services you want to activate (including Contacts) and press Save.
I wasn't able to achieve my goal of having identical contact lists in Gmail, Outlook, my Mac's address book, my iPhone, and my iPad, but I came pretty close: when I was done with three hours' worth of cleaning, exporting, and importing, the five repositories each had between 597 and 605 entries. Those are numbers I can live with.