Please.  Make your dissent heard instead.

Go to your polling place.

Get marked down as taking your ballot.

Put it directly into the box.

Imagine both parties analysts' and candidates trying to spin the following ticket results as positive and plan for 2010:

Democrat Candidate: 2500 votes

Republican Candidate: 2500 votes

Green/Other Candidate: 150 votes

Total ballots counted: 7000

 My point being, if you truly are unhappy with both parties and the sprinkling of alternatives and/or you are worried about “throwing your vote away” or even the possible harm a protest vote could make, just turn in an empty ballot, don't become invisible and uncounted.  If you stay away, the numbers to account for you will be estimates and much, much easier to spin.