It has some crash problems, but the $1 Seismometer app for iPhone looks like fun if you want to record vibration levels. Apparently it is so sensitive that some users say it can notice your heartbeats.
Which, you know, it is perfect for lame huh-what-was-that East Coast earthquakes. [iTunes]
https://gizmodo.com/all-the-videos-of-the-east-coast-earthquake-updating-5833659
