I have a very reliable earthquake detector right in front of me, on my wall. It's this:
My lovely, historical Tulsa plate has not been wrong yet. Actually, it's the plate-holder (the kind with the springs on the back) that alerts me. The wall this is hanging on is in fact the south side of my chimney. Airplanes and loud vehicles can make my windows shake, but this has "gone off" when all is quiet.
The rather large (for Oklahoma) one we had a couple of months ago was by far the strangest sounding. I could not figure out what the noise was because, besides the plate doing it's thing, other parts of my house vibrated as well. That was when I started to make the connection. And with that one, I began to mark down precisely when this plate vibrated. And lo, it's right on. Last night it went off around 9:38; wasn't a very strong one. I feel like I should DO something when this happens. Twitter it? Well there is an actual study going on using Twitter as faster earthquake notification. And I found that there is a website I can report these too. I feel like its my duty ;-)