Most of the time I find something I can work with in the SimV files. It's been so long since I've logged onto avsim or simouthouse that I've forgotten my passwords.
About the only thing I don't directly work with is making the actual aircraft model and sceneries (other than running one of my CFS1 installs with the FS98 world sceneries and changing a few default textures to suit a WW1 install). Also, source regardless, great many planes' textures rely on the program's poor shading abilities -- smaller protrusions and curvatures can be entirely missed with flat color textures or look so unnecessarily unnatural when details are represented with just plain lines. The models prove good enough once I redo the textures.
I also tend to fly and make my own missions for WW1 and WW2 aircraft although I've managed a few for the Korean conflict. I suppose wandering into Vietnam and the Middle East would warrant later aircraft but, to be honest, that hits a little close to the reality of my past.