I have a few ideas of my own (sorry if some of this or all of it has aready been mentioned).
Resources
Titanium: Used to make advanced military units mainly tanks and aircraft.
Nickel: Used in several industrial possesses sinse the late 19th/early 20th centuries. Also required for WWI and WWII era units as well as batteries for electricy.
Zinc: Needed to make brass with copper. Again used in several industrial processes. Also for music (instraments), coinage, churches (toll bells) and shells for tanks, artillary as well as munitions in general. Also used in some early gunpower units.
The following food resources would add some "colour".
garlic (good for health), dates, figs, apples, cherries/berries, pinnaples, coconuts, tea, game birds (grouse, turkey, pheasent etc..), bison/buffalo.
Units:
Ancient Units: slinger, javilan thrower (peltest, scirmisher etc..)
Classical units: light and heavy calvery, hoplite.
Middles Ages Units: foot knights (does not require the "horse" resource), heavy crossbowman, two-handed swordsmen, halberdtier, bombard (early gunpowder seige weapon)
Renniasance Units: Hand gunner (primitive gunpower (pistol) unit)
Industrial Units: gattling gun, morter.
Modern Units (WWI/WWII): WWI tank, WWII tank, mobile artillary (looks like tank except no turret - gun is fixed to fire forward only), WWI bi-plane/tri-plane, dive bomber, jeep, half-track, torpedo bomber, deisal powered sub (as opposed to modern nuclear powered sub), cruiser, radar base (another building perhaps?)
Modern Units (present) SAM missile base, armoured hummer, "nuke" silo (might be a building), scud launcher, tacitcal missile base or "nuke".
Also, railroads should also be aloud if player civ has access to oil or electricty.
What about telephone and television techs. Both had a huge impact on modern civilization.
What about more than one special unique unit per CIV?
Leaders: Vercingetorix (Celts) Was warchief who united quarraling celtic tribes to fight a Roman invasion led by Julius Cesaer. Gallic wars occured in the mid 1st century BC.
Anyhow that's all my ideas for know. I hope you find them of at least some use. Thanks.