I'm familiar with Timeline so this wasn't too hard to make. But no matter how good you are at it, it's still a tedious process. There's a lot of information that needs to be available and compiled in order to create an effective timeline. It's also more exciting when there's other media that can be pulled in besides just photos – things like tweets, Facebook posts, videos, etc. The more interactive, the better. It also has to be something that presents itself well in a linear format – whether it be the events of a day, a year or ten years.
I think all of these elements along with length of the timeline and relevance (no one is going to care about an Obama timeline right now) can make it a cool multimedia piece. Especially if it's paired with something like an article or a video, it works even better than just a standalone.