I think the key issue for 2008 is reducing the power of the executive. As some have pointed out, as the US increasingly centralizes power in one branch of government, our checks and balances are overturned in a way reminiscent of fascist coups. It doesn't matter who is president in 2008 or 2012, what matters is the fundamental process of democracy.
"With the gutting of traditional checks and balances, we are no less endangered by a President Hillary than by a President Giuliani - because any executive will be tempted to enforce his or her will through edict rather than the arduous, uncertain process of democratic negotiation and compromise."
Ron Paul is a republican who seems to actually believe in Less Government. As such, I support his presidential bid. I am a one-issue voter, because that's the way the system is. And my one issue is less government.