I would enact the following:
Two term lifetime limit for all elected officials, regardless of term length.
Campaign contributions limited to $1000 per citizen, $1000 per organization.
Get rid of the electoral college. A straight-up popular vote would be counted instead.
All laws must be seperate and distinct. One law may not modify another law. If "modification" is needed to another law, that law must be seperately repealed and re-enacted with the modifications. Require a publicly available "Version Control" (think CVS / Subversion / VSS) of all laws.
All laws passed must have a five year (or less) duration of action, after which the law loses effect. To stay in effect the law must be reviewed and re-enacted.
All laws passed must have a detailed description (in english not legalese) of what the law is trying to accomplish (why it was passed in the first place). This way we can keep track of why things are the way they are, and whether they are working or not.
Amend the constitution to make personal privacy an explicitly stated right of citizens.
Abolish all overtime exemptions.
Repeal DMCA and reduce copyright back to it's original 20 year period, retroactive to the beginning of time.
Repeal PATRIOT act.
Prevent banks from charging any fees related to accessing your money in your account (ATM Fees, Teller Fees, etc..) Also, require balance transfer fees (between credit lines) to be a fixed dollar figure (no percentages), that is no more than twice the bank's actual cost of creating a new account and transferring the debt.
Nullify all contracts that allow the contract to be modified in any way. Need a contract modified? Draft a new one with the modifications, sign it, destroy old contract.
Require a declaration of war before any hostile military action is taken.
Require that the USPS provide an option to opt-out of recieving any mail not addressed directly to an individual. Also make a "Do-Not-Mail" list similar to "Do-Not-Call".
Make the civil courts a "loser pays both" system.
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And these from sully:
Legalization of marijuana, decriminalization of the rest.
Vastly simplified tax system. Can't cheat the system if it's dead simple to calculate.
Those facing charges in the criminal justice system do not have their names published in the national media. If they're truly innocent before being found guilty, let their names remain relatively unsullied until a judgement goes against them.
Repeal the can't vote if you're a felon law. You serve your time, then you're done. The right to vote shouldn't be revoked for good.
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And this from JoshGuru:
Benefit/cost calculations published for ALL government spending.