Patents are covered by federal law, which to some degree can permit selection of the location where a patent infringement suit is brought. Perhaps not surprisingly, there is an uneven distribution of patent infringement cases among the federal district courts.  As might be expected, courts with the greatest number of patent cases are generally located in high population and/or high-tech areas.  However, there are some interesting exceptions.
One interesting peculiarity is the well-known U.S. District Court for the Eastern District of Texas which carries a vastly disproportionate amount of patent infringement cases.  This has been happening for some time, as can be seen from this 2006 article.  In fact, of the approximately 2,600 patent cases filed in 2009, over 240 were filed in the Eastern District of Texas.*  Another popular court is the District of Delaware, where approximately 230 patent cases were filed in 2009.*
Of course, opposing parties will sometimes attempt to transfer out of one jurisdiction into another. In this regard, the Federal Circuit may be starting a trend towards requiring stronger justification for initial forum selection, as two recent cases involving transfers out of the Eastern District of Texas suggest:
*A useful website for searching information on federal district court filings according to subject matter, location, or other parameters