A more on-target message to young voters would be "Get informed, then vote!" Any idiot can pull the lever in a ballot box; it demonstrates no great, admirable civic virtue merely to cast a vote, not knowing whom or what you are supporting by your vote.
Don't get me wrong, I do hope many young people will vote, but only after they have informed themselves about the issues and the positions of the candidates they will vote for. Along these lines, a resource for young voters that is an alternative to RocktheVote.com is RedeemTheVote.com, a group which aims to "register people of faith regardless of party affiliation, or personal political beliefs, but as a matter of Christian principle, that people of faith must be engaged in the political debate and vote as a matter of moral imperative... It also "reach[es] out to both parties to find the best in both, and find solutions to the debate, not trump or destroy one person or party."
Also, please see my previous three posts, for many links to resources on Election 2008.
Resources for Christian Voters- Election 2008
More Resources for Election 2008: The Issues
A Critical Election 2008 Issue: Supreme Court Justices