I use Bolt Depot for flat head wood screws:

    http://www.boltdepot.com/wood-screws.aspx

Brass, zinc-plated steel, stainless steel, and silicone bronze, in
various sizes.  If need be, I use brass screws dipped in gun bluing to
darken them to match blued screws.

Cheers,
Bill Wineburgh
http://members.aol.com/WWineburgh/