Are there any good interactive historical timelines?

Timelines are a good way of presenting historical information. There ought to be top notch interactive programs that can be used to explore history.

Some features that would be helpful:

1. Choice of what to look at and various filters. You should, for example, be able to chose to look at British literature in the nineteenth century if that is your interest.

2. Ability to look at multiple timelines. Looking at the political history of two different areas of the world on separate timelines might help to see interactions and parallel developments.

3. Drilldown capability. This would require a ranking of events in importance. This might be controversial, but the net effect could be very useful. You might want to study a war by first looking at the most important battles and then drill down to see some of the lesser ones.

It would be great if there was an agreed upon database format for storing the data associated with the timelines in the way that Excel is a common format for spreadsheets. That way people could provide different sets of data.