Earthquake early-warning system gave 10-second alert before Napa quake felt
A few seconds warning seems like it might be kind of useless for humans, especially at 3am, but it would be cool to have this feed into automatic systems to automatically put them in a "safer" state before an earthquake hits.  It might even be that 10 false positives a day are worth it to catch one real event, if the "safing" operation is relatively non-disruptive.