I got a snail mail from United for magazine redemption. One of the option listed is "The Economist" for 3200 (or 3300) miles, 51 issues.
Unfortunately, I didn't see any mention of a website.
How were you supposed to proceed if you did want to order? Were there many appealing choices besides "The Economist," or mostly drek?
IIRC, when I looked sometime back at subscriptions available through UA on the .bomb, I saw only my local paper and the WSJ. The 13-week WSJ offer was a good one, so I gave up 1200 UA for it, and it has proved still a better one since the paper is still coming daily more than 13 weeks later. (What is the longest anyone has continued to receive the WSJ after their subscription should have expired?)