The reliably libertarian Republican Congressman Ron Paul from Texas has introduced the "Identity Theft Prevention Act," a bill that will require the Social Security Administration to reissue Americans a new SSN that would actually be restricted to use in administrating the Social Security program, not used as an all-purpose federal (and other) identification number.
For the pragmatic argument, he points out how the rampant use of SSNs makes identity theft for the purpose of illegitimately using other people's credit and bank accounts easier. But he also has a more principled argument, saying that some "members of Congress will claim that the federal government needs the power to monitor Americans in order to allow the government to operate more efficiently. I would remind my colleagues that in a constitutional republic, the people are never asked to sacrifice their liberties to make the job of government officials easier. We are here to protect the freedom of the American people, not to make privacy invasion more efficient."
The fate of this bill will most likely be similar to that of all the other bills the dauntless Rep. Paul introduces. But it's wonderful that he's out there trying. His speech introducing the bill can be found here.