Hexmap engine http://hexmaps.appspot.com
Inkscape Boardgames Extensions http://www.lysator.liu.se/~perni/iboardgameexts/
Cartographers' Guild http://www.cartographersguild.com/content.php?s=c553a164955f72808210e69bd5c484b1
HexDraw extensions http://social.consimworld.com/group/hexdrawusers
Hex Paper generator http://incompetech.com/graphpaper/hexagonal/
Graph Paper generator (incl hexes and other stuff) http://www.printfreegraphpaper.com
MKHexGrid generator http://www.nomic.net/~uckelman/mkhexgrid/
John Cooper's wargame art page, including counter icons and terrain tiles http://www.jrcooper.com/gaming.htm#terrain_tiles