You can do it when you go to the post office and the DMV, but the problem with them is that their job isn't to register, educate, and galvanize voters. Their job is to send/receive the mail, and register your car for the road, repectively. Most State boards of elections are on the financial end of the proverbial totum pole when it comes to budgeting. Not much better at the Fed. level, either.
Personally speaking, if I were in government, I would view our low voter turnout as a crisis, and would use the existing agencies to mobilize voters, not just "register" and "processs" them. But that's just me.
