First, I spotted Randy Seaver's posting, which led me to Chris Dunham's posting, which led me to my most recent Found! article, Serial Centenarians.
I do a lot of research and crank out lots of articles, but I found this quest especially challenging and rewarding -- and I think it's a pretty good example of developing a strategy to tackle a somewhat elusive research objective (in this case, finding a pair of family members whose overlapping lives had spanned the entire 19th and 20th centuries, along with a touch of the 18th and 21st centuries -- in other words, lived through every U.S. president other than George Washington). So if you've got a few minutes to spare, I hope you'll give it a read.