Antigua
Nelsons Dockyard
ADMISSION - US $8 for visitors, US $3 or EC $8 for locals. See - http://nationalparksantigua.com/visiting/about-nelsons-dockyard/

Philippines
Puerto Princesa
"For the Permit/Entrance Fee (includes the paddle boat going inside the Underground River) - Local Filipino Adult - Php175, (US$3.50), International Adult - Php250 (US$5)"
https://www.tripadvisor.co.uk/FAQ_Answers-g294257-d320343-t1666594-How_much_is_the_ra te_for_the_underground_river.html

And Malaysia too ... Non-Malaysians pay RM15 (adults) / RM10 (children) to enter the park. (Malaysians pay RM3 and RM1 respectively). (Kinabalu)

Yes - needs to be added to the list of countries operating this practice

Gunung Mulu - 15RM Malaysians, 30 RM Fpreigners. See - http://mulupark.com/plan-your-trip/#fees
But
Lenggong - "Lenggong Archaeological Museum opens every day from 9am to 5pm and admission to the museum is free."

This little exercise has indeed identified rather more countires doing so than I expected (or remembered!!)
Asia
Almost all of SE Asia (But not Vietnam???)
Indian Subcontinent - universal
Near/Middle East - from Jordan/Lebanon to Iran (but not Turkey/Israel or Arabian Peninsular). I haven't been able to discover anything for Syria (Palmyra??) but suspect that it does/did
N Asia - not done (Stans, China, Japan etc) - except that 1 very strange "Anomaly" from Hahoe in S Korea!!!
Americas
Most of Central America (S of Mexico)
S America - only occasionally - Ecuador (fairly common) and Peru/Bolivia with 1 e.g each - but not universal in any? (Might we have missed some?)
Caribbean - quite common but not universal across all the islands.
Europe
Only Russia has any?
Africa
Universal across most of East and Southern Africa from Ethiopia southwards - except RSA where it is only "occasional" (??)
Only Ghana in W Africa (seems unlikely???)
N Africa - apparently not - though am very surprised re Egypt?
Oceania
None - as yet?
I looked up Nan Madol and it appears that you pay local land owners whatever you can negotiate in order to cross their land. Can't find either for Chief Roi Mata -seems to need a "tour" anyway.

Regarding the "size" of the "Mark up" - "Tenfold" doesn't seem unusual (as per Khao Yai in Thailand which started me along this track!) - India holds the record with its normal mark up from IR30 to 500 and Petra the individual one - JD1 to JD50!!! I suspect the average is nearer 4 times? Some seem so small as to not justify even doing it (E.G Quito Cathedral from $2 to $3)!!!

It might be nice to have a "map" with those countries having the practice in one colour, and those with just a few e.gs in another. Any views as to what is the best software to use for such maps. No doubt there are other "Country related" WHS aspects which we could use such a map to show?

As would be expected, Nicaragua follows the practice adopted by other C American countries and operates dual pricing at
Leon Viejo -
"admission is C$12 for Nicaraguan residents and US$2 for foreigners (c60C$)" BUT the US$2 includes a guided tour!!!
See - http://www.madeincentralamerica.net/2011/10/

Indeed!
I found this for Nubian Monuments e.g Abu Simbel
Includes admission to the Great Temple and the Small Temple. Tickets for the Sound and Light show [link – popup Misr Sound and Light] must be purchased separately.) - Egyptian: 4 LE, Foreign: 70 LE

This index page for Egyptian Antiquities shows that a number of such historic WHS operate dual pricing
http://www.sca-egypt.org/eng/SITE_List.htm
So
Ancient Thebes e.g Luxor Egyptian: 2 LE Foreign: 40 LE
Pyramids - e.g Pyramid of Khufu: Egyptian: 20 LE Foreign: 100 LE

Still trying to find
Abu Mena
Wadi el-Hitan
Historic Cairo
St Catherine

We haven't looked at Argentina and Brazil yet I believe.
Argentinian side of Iguazu has indeed lower prices for nationals

In Argentina it is widespread. They mostly have a 4-layered variation: for locals (those living in the same province as the WHS is in), for other Argentinians, for Mercosur nationals (or other Southamericans) and other foreigners

I note that the new arrangements proposed for the Taj Mahal, to limit the number of visitors daily to 40,000, are ONLY intended to apply to Indian Nationals entering for IR40 (or free in the case of kids).
Interestingly , the news source used by Els to report this (New Delhi TV = NDTV) didn't mention this -
www.ndtv.com/india-news/taj-mahal-tourist-entry-to-be-capped-at-40k-for-maximum-3-hou rs-1795060

It WAS mentioned by the Times of India however -
https://timesofindia.indiatimes.com/india/indian-visitors-to-taj-mahal-to-be-capped-a t-40k/day/articleshow/62344330.cms
It would have been rather stupid of Indian bureaucrats to prevent foreigners entering at IR1000 each whilst allowing Indian Nationals at IR40!

I wonder if this could be the shape of things to come in other overcrowded WHS which operate differential pricing. BUT - as far as I can see Peru isn't operating a similar system in its recent Machu Picchu restricted entry rules - presumably Peruvians are not likely to form a very large %age of the daily MP total unlike Indians for the Taj.

Indian Nationals can still get in outwith the daily limits if they pay the IR1000!! It isn't clear whether the new daily restrictions would apply to SAARC and BIMSTEC nationals who pay IR530

The entry to Abu Mena is free for everybody, although a donation is welcome when visiting the new monastery from where you can get to the archaeological site.

In Russia, I've been sold tickets for nationals couple of times just by asking for them in Russian, no questions asked. And as for the State Hermitage Museum in St. Petersburg, it's 680 rubles when you buy through the Russian language version of the site, which is about 12 dollars, vs. 17.95 when you buy through the English language version of the site. Again, bought the cheaper tickets for many friends from Slovakia, never had any issues with getting tickets and it saves money.