As Jesse Walker noted earlier, recent revelations about the targeting of Tea Party and small-government groups by the Internal Revenue Service may mean that "we're looking at some old-fashioned, deliberate, Kennedy- or Nixon-style political harassment via the taxman." In fact, the use of the ever-intrusive and inquisitorial IRS as a political bludgeon by whichever party controls the executive branch has a long history, starting, apparently, as far back as the administration of Frankling Delano Roosevelt. In New Deal or Raw Deal, author Burton Fulsom, Jr. (admittedly, no FDR fan) devoted a chapter to the early use of the IRS as a political hit squad.
The chapter delves at some length into the politicization of tax collectors under the Roosevelt administration, including not only its use as a hit squad against critics, but the tight leash on which it was put when friends of the administration were involved. But perhaps most telling is a comment by Franklin Delano Roosevelt's own son:
"My father," Elliott Roosevelt observed of his famous parent, "may have been the originator of the concept of employing the IRS as a weapon of political retribution."
Keep in mind that the IRS isn't dangerous and politicized because it's wielded by the Obama administration. The tax agency has been abused and used against political enemies by presidents of both parties. The IRS is dangerous because of its vast, almost unaccountable powers, and the temptations those pose for politicians.