Everything is connected to some extent. We know for example that solar cycles affect the weather down here on Earth but I would not have suspected that solar activity could be related to earthquakes on our planet.
It is as of now a tentative hypothesis but it makes some good sense, it seems.
Read more at NASA Science News (found originally at Washington Blog).
Update (Aug 23): it seems I got it totally wrong. It does not seem to be able to trigger earthquakes, in spite of Earth and Sun vibrating in the same frequency and fancy stuff like that. At least a connection has not been found as of yet.