I really like this idea. Creating a life timeline is something that I have thought about doing in the past couple of years when I realized that I couldn't always remember when such or such event happened. (e.g. "did we move in 96 or 97? It was definitely after Junior High but…")
However, I have to admit that for my personal use I'm not sure I would want to use it, just because I don't like the idea of putting a personal timeline in a service that might not be around in a few years, let alone in a couple of decades.
Note that I didn't mean to be negative about your product. I'm sure your goal isn't to lock information down without a way to get to it. It's more that from the examples the one that resonated the most with me was the life timeline, and I feel that's the kind of information that I would want to last "forever" and that I might be more inclined to implement myself for that reason. (a simple version of it)
Ideally, I would even love a timeline gathering all kind of information. Some kind of ultimate mashup of timelines, with pictures, movies, events, people… that link to Picasa/Flickr, Facebook, Gmail… But that's besides the scope of Preceden :)
However, I have to admit that for my personal use I'm not sure I would want to use it, just because I don't like the idea of putting a personal timeline in a service that might not be around in a few years, let alone in a couple of decades.