There's a lot of places in the National Register of Historic Places, and most are typical, common, and rational things: 18th-century houses, early skyscrapers, old farmhouses, early canals, etc. There's some things in the National Register which are positively unique or are things you wouldn't expect to find in the listings.

Some examples:

~ The cable cars of San Francisco LINK (http://en.wikipedia.org/wiki/San_Francisco_cable_car_system)
~ The first ski lift in the world LINK (http://en.wikipedia.org/wiki/Proctor_Mountain_Ski_Lift#Chairlifts)
~ A ranch house in Macon, GA, that personifies suburban development in the 1950s (featured in a Wall Street Journal article) LINK (http://en.wikipedia.org/wiki/Joseph_and_Mary_Jane_League_House)

Any other unique or unusual listing in the National Register of Historic Places?

Riverside Plaza in Minneapolis. Also known as the ghetto in the sky or the crackstacks. Added to the list on December 28, 2010
http://i.imgur.com/Dfu1J.jpg

That National Register has great value...

...but when preservationists try to save shit like that they do the preservation concept great harm.

^^The reason Riverside Plaza was added to the National Register of Historic Places is because it's a classic personification of 70s modernist/brutalist architecture and a well-preserved example of mid-century urban redevelopment.

Sure, today most people find it an offensively ugly and garish structure, but it's still pretty amazing in its absolute hideousness. 50 years ago, cities around the country were tearing down buildings that were then thought to be outdated, in need of maintenance, and ugly, and what do you know? Most of them were beautiful and remarkable structures razed in the name of "progress" that we're still grieving the loss of today.

That's why some architects and architecture fans like it, but I doubt (and it doesn't seem like) any of that means much to the average American.

Even in the 1960s and 70s, there was quite a bit of love for prewar buildings. The groundswells that led to a lot of 1970s preservation were based on an affinity for older architecture that's far deeper than what we see today about midcentury stuff.

The Taj Majal at Randolph A.F.B.
Its basically a water tower but its gorgeous:
http://www.rootsweb.com/~txpstcrd/Towns/SanAntonio/RandolphAFB.jpg

I love Riverside Plaza, I don't even think it's ugly, just very unique.

Concrete streets aren't anything special, but the first concrete street in the US is still in use and is still the original pavement.

~ Court Avenue concrete street, Bellefontaine, OH LINK (http://en.wikipedia.org/wiki/Court_Avenue)

A chicken coop is pretty mundane, but the chicken house at the first broiler farm in the world is preserved.

~ First broiler house in the world, Georgetown, DE LINK (http://en.wikipedia.org/wiki/First_Broiler_House)

What's the point of having a subway station (especially from NYCS) or highways on the NRHP if they're not even state[local] mantained?

^^The reason Riverside Plaza was added to the National Register of Historic Places is because it's a classic personification of 70s modernist/brutalist architecture and a well-preserved example of mid-century urban redevelopment.

Sure, today most people find it an offensively ugly and garish structure, but it's still pretty amazing in its absolute hideousness. 50 years ago, cities around the country were tearing down buildings that were then thought to be outdated, in need of maintenance, and ugly, and what do you know? Most of them were beautiful and remarkable structures razed in the name of "progress" that we're still grieving the loss of today.

What are the conditions in Riverside Plaza? Is it still public housing?

Anyway, Riverside Plaza is not the only subsidized / public housing to be listed. Raymond Hilliard Homes in Chicago is listed as well.

http://farm4.staticflickr.com/3601/3333824182_79c23a577d_z.jpg

What are the conditions in Riverside Plaza? Is it still public housing?

Currently it's about half market rate, and half subsidized housing. Most of the residents in the complex are Somali immigrants.