North East Wargaming Society:  All the tournament information for Historicon, Cold Wars and Fall In.

Historical Miniatures Gaming Society:  The hosts of Historicon, Cold Wars and Fall In among other things.  Good site for links and tournament info.

Foundry Miniatures:  Gold standard for metal miniatures.  Their historical range for Ancients is fantastic.  They are also pretty pricey.

Warlord Games:  Very nice, if limited, range of plastic ancients with some metal units as well.

Reaper Miniatures:  Incredible line of fantasy and other figures in metal.  Great for role-playing and special characters in units.  Also, I use their pro paint line for most things.  I like their triad colors (color, shade and highlight sold together).