This morning in Boise, Idaho I woke up to what felt like a very, very mild earthquake. Nothing shook enough to make any noise, but I could feel the bed shake just enough to make me think that it was some kind of seismic activity.
A Google search showed me where to report this
http://earthquake.usgs.gov/eqcenter/dyfi/

One nice thing about going to that site was that it confirmed that it wasn't my imagination.
What I felt was:
10 miles ESE of Wells, Nevada (ID 2008nsa9) FEB 21 2008 06:16:05 PST 6.3