There's a sudden spurt of interest in going to a national voter-registration system. See Kevin Drum, Matt Yglesias, and Reihan Salam.
So it's time for me to renew my plea to do away with Social Security numbers. Implement a system that identifies eligible voters, potential patients (based on the recent RAND study) and taxpayers but at the same time phases out the use of SSN's. I'm convinced we could come up with a system that increases the safeguards for each person's privacy, gives people much more control over how their data is used and to whom it is available, and improves efficiency.
The key model is the virtual credit card number, not the one you're used to using but the one VISA offers which few people use. Most people give merchants their credit card number, which can be risky. But you can choose to have VISA provide a number that works only for the transaction, or the vendor. See this. Adapt the same principle and you can have a government-validated identification number for each employer-employee relationship, each patient-healthcare provider relationship, and each voter-voting district relationship; each different, each safeguarded, and none requiring an SSN.
Seems to me if you point out to reasonable people that they already have a unique identifier (their email address) and we get rid of the SSN it's a reasonable deal.