How do I export my Gmail contacts?

Actually, you're in luck. Apparently this capability was just recently added to the Gmail service, and it's relatively straightforward:

Log in to your Gmail account, then click on Contacts on the left side. You'll see:

Notice in the top right there's now an Export link. Click on that and you'll see:

This is about as straightforward as it gets! Choose between "Gmail CSV" (a neat idea if you have more than one Gmail account or want to share your address book with a colleague or friend, but generally probably not that useful) and "Outlook CSV" for the ubiquitous Microsoft Outlook email system. Before you panic because you're running Apple Mail or Thunderbird or some other email client, check your documentation: almost all modern mail programs can import Outlook format address books.

Once you choose the format that best fits your needs, click on Export Contacts and in the blink of an eye, you'll have a filename like "gmail-to-outlook.csv" on your computer, ready to be imported into another email program.

Oh! And one helpful tip: Microsoft Excel and other spreadsheets live and breath comma-separated-values (CSV) files, so if you wanted to prune your address book before importing or distributing it, opening up the file in a spreadsheet could be your simplest solution.

Hope this gets you going, and for those of you still looking for Gmail invitations so you can get accounts of your own, please do read Can I have a free Gmail account?