I've heard several stories concerning the difficulty in registering to vote. This one is one of the more blatant scams: AlterNet: Election 2004: Democracy in a Trash Can:

On Tuesday, Nov. 2, when hundreds and perhaps thousands of registered Democrats enter their polling places in Nevada, they will be in for a rude surprise: They won't be allowed to vote. Even though they filled out their registration forms properly and they did it way ahead of the deadline, there will be no record of their being registered to vote. That's because, according to an investigation by Las Vegas television station KLAS, a private voter registration company called Voters Outreach of America - an outfit largely funded by the Republican National Committee - has trashed hundreds of registration forms of registered Democrats."

I've also heard a number of anecdotal stories about the difficulty in getting absentee ballots overseas. One person repeatedly requested, in writing and by phone, an absentee ballot for himself and his wife. Eventually, the ballots were FedExed to him at his own expense to ensure delivery. Cost in phone calls and registered mail to get the ballots? Something over $30. Democracy ain't cheap, y'know.