Hello,
I have recently been using kicad for some analog circuits (audio preamp for interfacing with fpga dev board) and had the need to do simulation verification. I found that kicad provides a pretty good netlist generation tool which can be used with spice.
I documented my workflow for simulating kicad schematics using ngspice & ngnutmeg. I thought it might be useful for others.
Blog Post:
http://stffrdhrn.github.io/electronics/2015/04/28/simulating_kicad_schematics_in_spice.html
Github Project: