Wolfang Pesendorfer wrote a neat piece on why it is often rational to abstain from voting if you are truly ignorant of the issues. This is how I rationalize not voting in obscure elections, and hate the "rock the vote' campaigns that equate voting with goodness, irrespective of one's knowledge base or preferences (I'm sure they wouldn't want Nazis voting, but of course they think every kid who votes will be a typical liberal American).

“Abstention in Elections with Asymmetric information and Diverse preferences”, Pesendorfer and Feddersen, American Political Science Review, 93, Number 2, June 1999 pp. 381-398.