Just sitting here playing around with Erlang and Mnesia's database replication when I felt what can only have been an earthquake.
It wasn't very big (this is the UK, after all) but it made the house shudder quite strongly.
I've felt one here before. That was more like a very low rumble, quite a strange sensation, but I don't remember it making the house move to the same extent as this one.
I tried to check with the British Geological Survey Seismology Home Page but it seems to be down at the moment. Have to try again in the morning.