Puffy Planet

Hat-P-1, discovered by a team led by Gaspar Bakos of the Harvard-Smithsonian Center for Astrophysics (CfA), is way too big for its mass. Finding extrasolar planets that do not match known physics or planetary formation theories might cause speculation about engineered worlds. Being located that close to the star might seem unwise, but, on the bright side, locating close to the local natural nuclear fusion reactor would solve your energy problems. Astronomers will probably eventually find a source of energy that is enlarging it. If not tidal forces, then some other source that hasn't been considered, such as the magnetic field of the star, high-energy particles in the solar wind, or even sound waves causing some kind of standing resonant waveform could be the explanation.
http://www.cfa.harvard.edu/press/pr0624.html
http://www.space.com/scienceastronomy/060914_cork_planet.html
http://news.bbc.co.uk/2/hi/science/nature/5346998.stm