A few months ago, my husband and I received a gift subscription to Netflix—an online movie rental site. The unlimited, one-at-a-time subscription meant we could have as many movies a month as we like, but only one in our possession at a time.

We had only vague familiarity with this company and site, and weren't very excited about the seemingly troublesome process it likely offered. But we decided to give it a try; after all, it was free.

We navigated our way around the site. And being a diligent skeptic of online offers, I dug deep. I read through the endless fine print of the gift subscription. I discovered we had to enter our credit card information to activate it. I don't like this sort of thing. Then I saw the way out summarized by two little words. If things didn't go well we could "cancel anytime." Thus re-assured, even if still a bit reluctant, my husband and I signed on.

After a couple weeks, watching a movie every few nights became a habit. Though we hadn't been big "movie ...