- The Tsukiji Fish Market could take each of the sea resources (whale, fish, crab, pearl, clam) that you secured, and create two additional copies for each. Instead of having "2 whale, 3 clam and 1 fish" --> "4 whale, 5 clam and 3 fish"
- The Bourse (you are meaning the 1602 one in amsterdam, founded as a commodity exchange, right?) could probably also create additional resources - I'd say of all "renewable luxuries". So, 1 additional spice, pearl, fur, sugar, coffee, tea... for each 2 of them that you have secured via colonies or trade. (Should obsolete eventually in the industrial/modern era, when the effect downgrades to a mere +25% wealth bonus which will still be nice)
- Torre de Belem: +1 copy of each happiness luxury in BFC of that city? (as additional effect?)
- porcelain tower: +1 copy of each health luxury in BFC of that city? (as additional effect?)
- house of wisdom: + 1 copy of each common health resource in BFC of that city? (as additional effect?)
- probably some others, but they should always be related to famous trade institutions instead of the usual prestige wonders
so, some more that I just invented:
- There might be some rather early wonder (Great Quarry?) that would allow you to create one copy of stone and marble out of thin air. I was first thinking of Carrara here, but I'm uncertain: Should it require at least existing copies of both (then early civs like Babylon, Rome and Egypt would qualify) of should it require ~10 mountains in the BFC?
- More specific and smaller, a less expensive wonder like "World Diamond Exchange" (no specifical archetype) could take 1 gem and create 2 copies for trade or the domestic happiness. Requires a gem resources that is not controlled by yourself, but traded in?
- Muscat trading harbor: +1 copy of both spice and pearls, provided you have one of each already, requires the economy civic to be "below" free enterprise (e.g. redistribution, merchant/regulated trade), requires no grassland tile in BFC
- Silk Road Hub: +1 silk. Must have a silk resource, "silk road" must be present, must not be in Chinese core. (Was thinking of Kashgar, Samarqand or Constantinople here)
- Fair Trade Coffee Society (requires social welfare), doubles your copies of coffee available, commerce bonus for each coffee plantation around that city, light commerce penalty for all rival coffee. Requires Public Welfare.
- Farben AG (cribbed from the Germans who were front-runner in the Chemical Industry --> late wonder, provides 2 dye resources out of thin air)
not sure if the next one shouldn't be rather a national wonder?
- Planter's corporation: +1 copy of all luxury resources that are obtained from plantations/orchards, heavy commerce penalty on all plantations (because e.g. the planters corporation in British Ceylon or in Brazil, DID create a resource boom, but at the same time overproduced and fell victim to prize instability.) Requires the civics of isolationalism/colonialism combined with regulated/free trade, may not be built in core. Maybe requires the Trading Company as present?
more national resource wonders
- Central Breeding program (+1 copy of sheep, cow, pigs, if you control at least one). I'd say it should require at least a +10 healthy city. Also, a rather high tech requirement, late renaissance+
- Central Zoo (+1 copy of camels, horses, ivory - if you control at least one). Needs a healthy city, like above, and even higher tech requirement. late industrialism+
- The National Seed Vault could provide one extra copy of all plant based resources in the game (wheat, potatos, rice, corn, banana), whether you control one of them or not. late modern era+, hyper-expensive
- The Global Seed Vault (WW again) would require the National one, provides again one extra copy of the above, plus one copy of each of the luxury plants (spice, cotton, wine, coffee, tea, sugar). Even more hyper-expensive. Is it possible, to allow two copies of a world wonder?
Don't know if there are also plans are to tie the use of strategic resouces to some limits - like iron, uranium, coal and oil? I mean, I can imagine restrictions like "one coal can only provide enough energy for two coal plants", "one uranium only for three nuclear plants". Could you restrict the number of factories to the number of all coal+iron+oil resources available in the empire? There are many possible national wonders and/or world wonders all around special industrial parks, like "Motor City" (+7 cars?) or "General Oil" (can substitute oil for coal) or "Standard Coal" (can substitute coal for oil), that require the presence of resource-exploiting companies. But as much as I'd like to have them, I already imagine how easily the technical advantage of a human player would dominate all AI competition.
If you tie things down in even more detail as suggested above, you get into the gritty details fast. I know it from Realism Invictus. There are entire industries that require 1coal+1iron to create 1steel, and 1steel to create 1cars, and the cars are a happiness resurce. 1steel can also be used for 1gun factory, or 1rocket factory. Brick industries, Furniture industries, household appliances industries, manufacturer specialists... it IS a great mod, but I don't think you're going in that much detail.