While certain wonders are certainly unique, there are others which certainly are not. West point/Sandhurst is an excellant example. Each empire should be able to produce one of each of the 'demi-wonder' types. Obviously they must not replace other wonders or amienities, and should only affect the city they are in, so you have to choose carefully where you build them. Some examples

Military Training Academy: The top training centre in the country. City and all cities linked to it by trade routes produce veteran units.

National Space centre: The place where all major space launches take place, and large amounts of spin off space research. All science in cities with trade routes to this city (not city itself) have +75% effect of science amienities.

Secret aerospace center (Skunkworks): Halves prototype developement cost of aircraft.

Saint (fill in the blank)'s Cathedral: 2 unhappy citizens in city become content.

Also, I REALLY HATE the protyping thing from SMAC, it was pointless, and is an example of where realism was taken too far, realism should be focused on trade, war etc.

Palace: classic effect.

Academy: acts as full barracks in home city, allows barracks in other cities to produce vet units (otherwise just have repair function).

Religious center?: allows building of cathedrals.

Nuclear test: allows building of nukes. unhappiness.

Space center: allows building of spaceship parts.
(I hate wonders which give benefits to all civs equally)

NOrad: acts as SDI within your borders.

Postal Service - Increased efficiency.

Mobile Phone Network - Increased production.

Secret Police - Reduced corruption, (decreased happiness)

National University - Increased Science output (increased McDonalds sales)

postal service and mobile phones- these should be advances which give an efficiency, these don't belong in a particular city. National universtiy is similar, even if you mean the best in the country, there are usually at least 2 that can claim to be that. Norad = SDI? That just doesn't make sense, seeing the absense of SDIs today.

Some more suggestions:
Communications HQ- something like can view inside all cities within, say, 20 squares.

Postal service - quite a good example of one per civ needed. increased efficiency? is that the same as reducing corruption\waste? And if so, don't we have enough of this kind? seems like a dud demiwonder. Try for a different effect. the efficiency angle doesn't seem to fit, anyway.

Mobile phone network - I like it. but production? how about trade instead?

National university - I don't get the idea, and I think a science wonder with a national effect (one that's not just a ____ in each city, ala SETI) runs the risk of being too powerful in ICS brand civs. more data please.