Telephone directories may take quite a bit of work to compile, but perhaps more labor than creativity. I can't off hand think of too many ways to organize such a directory.
I can immediately think of many ways to do dates, and so can many java programmers (think the Date api, the Calendar Api, JodaTime, JSR310).
And having "new Date(1,1,1)" mean "the first day of the second month of the year onethousandninehundredandone" surely requires a bit of creative thinking.
Telephone directories also take quite a bit of work to compile, yet (per Feist) can't be copyrighted.