I was startled recently to find two young people (30, 24) who had never heard of traveler's checks, something that was ubiquitous in my youth. Part of the anticipation of a trip abroad was going to the bank & buying them, following discussions of the most useful denominations & just how much money you would need for the entire trip. After a highly scientific poll of everyone I ran into & remembered to ask, I discovered that age 40 is approximately the line between having used them & never having heard of them - they had an idea of what they were but had never seen these checks themselves. A couple of people thought they weren't a bad scheme, like the kid who came up with the ingenious idea of a phone that's attached to the wall so you wouldn't lose it.
If you have a burning need to know more, here's a short but thorough article.