Machu-Pichu - Allows a city to be built on a mountain square or, alternatively, allows a city to remain hidden somehow (This wonder would provide a valuable effect for modders who wanted to somehow represent hidden cities such as Gondolin in a Silmarillion Mod). Becomes obsolete with flight. Could alternatively be used as a forbidden palace type minor wonder.
Angkor Wat - A huge religious complex in southeast asia. I haven't really thought about effects, any ideas?
Taj Mahal - Same as above.
Nazca Lines - ????
Moa Statues of Easter Island - ????
Statue of Liberty - Can't believe this one already hasn't been included.
It can be used as a modern day Colossus that doesn't expire and/or gives bonuses for immigration (assuming immigration is implemented). Available only to Representative governments.
Eiffel Tower - Same as how it was done in Civ2. Bring it back!
Sacsayhuaman - This is a great Inca fortress which I think should be a minor wonder which provides 100% defense bonus (maybe more, maybe less) to the city it is constructed in. Expires with gunpowder.
International Space Station - Research bonus? Or maybe this is the wonder which allows the construction of a space ship to alpha centauri? The Apollo Program could be required for the construction of this and the Apollo Program's effects could be changed.
Marco Polo's Embassy - Remember this from Civ2?
Stone Henge - Perhaps gives 1-2 free techs upon completion?
Any others?
Angkor Wat - A huge religious complex in southeast asia. I haven't really thought about effects, any ideas?
Taj Mahal - Same as above.
Nazca Lines - ????
Moa Statues of Easter Island - ????
Statue of Liberty - Can't believe this one already hasn't been included.

Eiffel Tower - Same as how it was done in Civ2. Bring it back!

Sacsayhuaman - This is a great Inca fortress which I think should be a minor wonder which provides 100% defense bonus (maybe more, maybe less) to the city it is constructed in. Expires with gunpowder.
International Space Station - Research bonus? Or maybe this is the wonder which allows the construction of a space ship to alpha centauri? The Apollo Program could be required for the construction of this and the Apollo Program's effects could be changed.
Marco Polo's Embassy - Remember this from Civ2?
Stone Henge - Perhaps gives 1-2 free techs upon completion?
Any others?