I always thought existentialism was the exclusive province of some continental philosophers.  Well, I was wrong. 
There appears to be a growing literature of psychologists investigating empirically the existential concerns of people as well as the psychological strategies they adopt to cope with existential concerns, the effects those concerns have on other attitudes, etc.

Apparently, the "big five" existential concerns are death, isolation, identity, freedom, and meaning. 

For more on this, there is a short introductory article in a recent issue of Current Directions in Psychological Science (requires subscription for reading).