Politifact offers up The Top 10 most viewed fact checks of 2013 and also, with some overlap, The Top 16 myths about health care law.
For those of you who aren't familiar with Politifact, it's a fact-checking project offered by the Tampa Bay Times. When it tells you that your political allies are correct and that your opponents are lying, it's a valuable, unbiased service whose integrity is beyond question. And when it tells you the opposite, it's a dishonest smear machine working for the opposition.