Hey Kortal,
I'm running pretty much what Lars_A is running. I'm using SFACT right now, which is a fork of skeinforge. It was really amazing how easy it was to get a really decent print after changing just a few settings, compared to just straight skeinforge.
I used to use repsnapper as well, but I find pronterface much nicer. Especially if you are using windows on your host computer.
As for firmware, I hear really good things about Marlin for the Gen6 boards and such, but if you're going with RAMPS or Sanguinulolu, sprinter seems to be the standard. I use sprinter and I really like it.
Hope this helped and good luck!
bdcannon