Hey, now I'm over 5000. What a chatterbox I am!!!
Kate, the show is slightly morbid, being that it revolves around a family who runs a mortuary. Each show starts off with someone's death, and incorporates the story of their life and funeral into each episode. The family and their relationships are horribly dysfunctional, all the while they are helping others deal with their grief. Check out the website at http://www.hbo.com/sixfeetunder/
for more info, episode summaries, obituaries of the people from each episode, and tons of other stuff.
I got hooked on the series after watching one episode, so I highly recommend it.