Four on patents
Bessen analyzes a broad range of evidence on the economic performance of the patent system. He finds that patents provide strong incentives for firms in a few industries, but for most firms today, patents actually discourage innovation because they fail to perform as well-defined property rights.
See also Bessen's recent paper co-authored with Michael J. Meurer, "Do Patents Perform Like Property?"
Forbes discusses the "standard of obviousness" and a few of the seemingly goofier patents awarded recently, such as a "method of exercising a cat" (U.S. patent 5,443,036).
A recent paper documents that over the last 20 years, U.S. patents have becom larger and more complex.