How hot does the sun warm up things on Earth?
"El Azizia in Libya recorded a temperature
of 136 degrees Fahrenheit (57.8 Celsius) on Sept. 13, 1922 -- the hottest ever measured."
http://www.space.com/scienceastronomy/101_earth_facts_030722-1.html
That may have been the hottest temperature ever recorded- according to how we measure temperature on Earth- 5' above the ground in a painted white wooden shaded box.

But as everyone knows if one leaves a car parked on a hot sunny day with the windows rolled up, it could get even hotter than this.

"The outside air temperature was approximately 80 degrees F. At 2:15pm just after measuring
the cars, the pavement in the sun measured 111 degrees..."
Car Color: Black, Windshield temperature: 130.3 F with car hood temperature: 160.0 F
http://tom-morrow-land.com/tests/cartemp/index.htm

Now, of course, car interiors can get hotter than this but, this only reference I could find mentioning the temps.
There is also a fair amount on internet about frying eggs on sidewalks- apparently you need something like 150 F.

According to EPA roofs can get to 190 F:
"Over 90% of the roofs in the United States are dark-colored. These low-reflectance surfaces reach temperatures of 150 to 190°F"
http://www.epa.gov/hiri/strategies/coolroofs.html

Asphalt roads probably get just as hot, but could find any specific reference to their temperature.

One reason I find this slightly interesting is I was wondering how hot you could make a greenhouse on Earth- if you trying to do this without using reflectors or other ways of concentrating solar energy.

It's understandable why people aren't very interested in making hot greenhouses or even any other type of buildings as hot as possible- as the preferred temperature is somewhere around 72F.
It seems to me that without a lot effort, one could probably create a greenhouse with the air temperature getting as hot as 190 F- using thermopanes windows and having it black or least dark colors in the interior.

Now, on the Moon there is the excellent insulative property of having near absolute vacuum, and it doesn't have about 30% of solar energy blocked by Earth's atmosphere, therefore even though it's the
about the same distance from the Sun, one should easily be able to get higher temperatures than 190 F.
It would interesting to know what max temperature would be on the Moon and using best material to obtain the highest passive temperature possible.

Now, getting back to Earth. Suppose one had greenhouse with very efficient thermopane windows and you were to fill the greenhouse with a mixture of most effective greenhouse gases and have it pressured
at say 2 atm of pressure and cover the ground with dark material. What would be the maximun possible air temperature inside the greenhouse?

And would it make much difference to have a very large greenhouse or significantly higher pressure of greenhouse gases?