There are millions of public calendars and event databases available online. From the Google and iCal Calendars of civic and social organizations to large commercial directories, these searchable listings are extremely handy for letting people know when and where important stuff is happening. Calendars are just another one of those beautiful web tools that we can't imagine living without. Indeed, publishing a calendar of events can be yet another indispensable service that makes your website stickier and more useful.
The only downside of managing a calendar is that time inevitably marches on. What was au courant quickly becomes irrelevant. Hundreds (sometimes thousands) of events must be updated on a regular basis or the data becomes useless. For user-generated event calendars that may not be a big deal but for larger event calendars, constant feeding and care is required.

A client of ours manages a database of thousands of USATF approved races came back to us again this year as he realized that his race listings were quickly becoming outdated. Most of the races are annual events but they don't always fall on the same dates year to year. Moreover, some races get canceled or renamed along with new sponsored races popping up all over. Along with upcoming dates, each race website had to be checked and re-verified. The whole process took us just a few hours using the crowd--a task that could've easily taken the client a week or more. Pricetag: a few hundred bucks.
I guess that must be why they don't let relay teams compete in marathons. However, in a race for data, passing the baton to a JobSpooler relay team could get you to the finish line without breaking a sweat.