A couple of sites out there catering to the earthquake-wary.
Earthquake probability forecast from the USGS shows a map of California color-coded with the probability of shaking ("the level of shaking that throws objects off shelves") in the next 24 hours. They fully admit that it's not likely to predict a big quake, but it might predict aftershocks of a significant quake. (Hmmmm. After a big quake, color that area red for the next 24-48 hours. There. I could make this map.)
If you haven't tried out Google Maps yet, I recommend it. The map is scrollable without reloading the page, and you can switch between map and satellite photo with one click. But what's got the web buzzing is that the technology they use to insert data points (basically pushpins with information about them) is something web programmers have been able to latch onto and use for their own purposes. Imagine, for example, that I made a web page with a fully realized map (scrollable, zoomable, with satellite photos, etc.), with pushpins at every stop Dana and I plan to make on our road trip this summer. Google essentially provides the really hard part (the map), I just provide the data.
It's interesting: Google does not officially support this kind of re-use of it's data, but they certainly know about it and haven't asked anyone to stop yet. Big question is if they will eventually close it off, or start charging for it, at least. Then again, if they can figure out a way to include their little targeted ads, then it may remain an available tool for developers everywhere.
But I digress. If you're here and reading this, feel free to add a comment via the link below.