HAT-P-1 System - A stellar binary believed to contain the planet with the biggest known diameter and the least dense. This would have been only the second planet with such a low density. Later measurements showed it wasn't that inflated, and has the expected radius for a highly irradiated core-less Hot Jupiter.
HAT-P-2 System - Hat-P-2b (aka HD 147506b) is the most massive measured exoplanet discovered that is clearly not a Brown Dwarf and the first transiting Hot Super Planet discovered. It is the first known transiting planet with a significantly eccentric orbit (2.8 to 9.3 million miles) and experiences significant seasons. It briefly held the record of furthest out transiting planet. It takes about a day to heat up and 4-5 days to cool down. Spitzer can measure different depths with different infrared wavelengths. Its temperature was mapped out. Its daytime is as high as 2400K, while its night is 1200K. It would have winds blowing thousands of miles per hour.
HAT-P-3 System - A heavy-element rich planet transiting a metal rich K dwarf star. Its small size 0.89 JR for its mass 0.6 MJ indicates it has a rocky core.
HAT-P-4 System - A low-density inflated Hot Jupiter around a metal-rich star. Its presumed high level of heavy elements presents a challenge for explaining Inflated Hot Jupiters. Perhaps it has both a dense core and an inflated radius?
HAT-P-6 System - An inflated Hot Jupiter (1.33 JR) around a bright F-type star. It's Jupiter-like mass (1.06 MJ) is higher than the other 5 low-density inflated Hot Jupiters known at the time of its discovery in 2007. Its star is one of the most metal-poor ones hosting a transiting planet. A small dense core is expected.
HAT-P-7 System - F8 star also known as GSC 03547-01402 containing a transiting Hot Jupiter and an outer Jovian and a further out stellar companion. Transiting planet was used as a test for the Kepler mission (dubbed Kepler 2), which was able to detect the planet's occulation, as well as evidence of phases. Very little of its heat is transported to its night side, with its hottest spot being 1,300 F hotter than its coldest spot. Its atmosphere could be made up of exotic gases like Titanium Oxide. The Hubble Space Telescope made its 1,000,000th science observation on this planet in the attempt to detect water in its atmosphere. The planet may "lift" its stars surface up gravitationally, reducing its temperature a fraction of a degree in a darkened spot that lags a few hours behind the planet. It was found by a Japanese team to be orbiting backwards only a day after the first retrograde exoplanet WASP-17b was announced. The Japanese team inspected two stars nearby, measured their proper motions, and found that one of them was a member of the system. They also confirmed an outer radial velocity detected Jovian between the planet c and companion star B. Star B is suspected of tilting planet c's orbit, which in turn affected planet b's orbit and caused it to orbit backwards.
HAT-P-9 System - System that contains an inflated Hot Jupiter around a moderately faint F star.
HAT-P-10 System - Known as HAT-P-10 and WASP-11, it was detected independently by both teams. Contains a semi-Jovian that experienced the third lowest insolation (solar radiation per area) of any known transiting planets at the time.
HAT-P-11 System - Star system 120 ly away in Cygnus with the second discovered transiting Super-Neptune and the least massive transiting planet known at the time. Also observed by Kepler and dubbed "Kepler 3b". Orbit unusually eccentric for a Hot Neptune (5 day period) and is inclined 103deg to its orange dwarf star's rotation. Natural radio waves may have been detected coming from the planet. Radial drifts may point to another planet. It was the first smaller planet found to have clear skies (the four previous planets studied were cloudy), which allowed its atmospheric composition to be studied, which was composed primarily of hydrogen and helium with some water (which would be over 1000F).
HAT-P-12 System - Contains a Saturn-sized transiting planet around a metal poor K star. It broke Saturn's record for the least massive Hydrogen/Helium dominated gas giant known to date. Being so hot, the planet is almost as large as Jupiter. Transit was detected by an amateur astronomer.
HAT-P-13 System - A star containing the first transiting planet (inner planet) in a multiplanet system. Important clues about dynamics and interior dynamics can be studied in this case. In 2010 it was found to be only one of the two out of all 79 known transiting exoplanetary systems that could not support a habitable Earth-like planet, since it is too close to the habitable stars.