Duhnt Da Da!
Well Dan, how deep do you want to go? Mostly I've focused on counters, but I have done a couple maps for different games.
The quickest option may be
HexDraw. It is fairly easy to use, and has been quite stable for years.
My current Favorite is
Inkscape, with the
Pelle Nilsson map extension. I like it because the finished map is scaleable. Working with the different layers is quite easy. Work through the
BGG thread for more information. Pelle also has a counter plugin which you may find useful.
The drawing tool in
LibreOffice is good. The zooming is a little clunky. Customizing colors and bitmaps is a little difficult. Once you master it, the results are acceptable.
At some point, you will want to visit
John Cooper's game site. I found[/size] the terrain tiles especially useful.