Thank you for your input! Too bad that no such thing seems to exist - unless someone else turns up something that I could use, I guess I'll work around it in some way. I'm somewhere midway between a planner and a pantser - I like to figure out lots of things about the character backgrounds, the world etc. first, let the story grow in my mind before I start writing, and set down scene ideas especially for the early part of the novel, but I also come up with plenty of it during the writing - and also for that, it'd be important to have the history timelines well documented! I've been able to make Scrivener work pretty well for my plotting and planning needs, but I can't find any useful way to deal with timelines in it.

And I bet it's hard to track down entries from years ago! At least unless you happen to have super-amazingly organized tags (I know I don't).