re: You should be able to register anywhere, but you get the blue ribbon for getting why I posted it.
At some point, someone who intends to intelligently exercise their franchise has to accept some responsibility for their actions, too, and people who waited until the last second to register need to realize that if they don't have time to re-register, it's at least partly their own fault.
At least in California, the voting system all but holds your hand through the whole process.