Some people really have a lot of free time on their hands. In this case Paul Bolster and Emery Trahan of Northeastern, who have done a full blown academic paper on the effectiveness of Cramer's stockpicking.
For those who would prefer not waste their time (with either Mad Money or the paper), here is the punchline: Cramer's stockpicking was in line with the market. One could replicate Cramer's performance by constructing an index composed of 18% Russell 1000 Growth, 29% Russell 1000 Value, and 53% Russell 2000 Growth.
In other words, for all his histrionics, Cramer is about as effective as your standard, two-sided coin.