Here are the steps:
- When you first started up your Nexus 7, you were required to set up a Gmail account. If you didn't do it then, just do it now. It's not that hard. And you don't have to use it; you only need to have it. You can set it up from any computer, by pointing your browser to http://www.gmail.com.
- Open your email program, or login to your browser-based email application. Go to Contacts or Address Book, and find a way to Export your contacts or address book as a CSV file. Most email programs can do this. (CSV stands for "Comma-separated values." If you open the file in Notepad to have a look at it, you will see that it's everything in your address book, separated by a bunch of commas.)
(Note for those who care: You can also export your contacts or address book as a VCF file, but the beauty of my procedure is that you don't need to. A CSV file works just fine.)
(Note for those who don't care: VCF stands for "Virtual Card File." I know; the "F" is redundant. Hey, I didn't invent it.)
- Log into Gmail. Click on the "Gmail-downArrow" button and select "Contacts." In Contacts, click on the "More-downArrow" button, and choose "Import...". Click "Browse" to find and select the CSV file you just created in Step 2. Then click the "Import" button.
You don't need to use Gmail on your Nexus; you can keep using your regular account. All of those imported contacts are in the People app on your Nexus, and your email account automatically knows about all of them.
UPDATE, FRIDAY 9:30 A.M.: This method doesn't import those collections of addresses known variously as Groups, Distribution Lists, and Mailing Lists. Neither CSV files nor VCF files were designed to hold lists like that. If any of my readers knows how to import Distribution Lists, please comment on this post and enlighten us. Until then, I guess you'll just have to recreate them manually.
UPDATE, ABOUT A YEAR LATER: As emil pointed out in his comment, you need to make sure that the Google account in your Nexus 7's Settings menu is the same one you use in Step 3 to import the contacts.