A New Constitution

Some men look at constitutions with sanctimonious reverence and deem them like the ark of the covenant, too sacred to be touched. They ascribe to the men of the preceding age a wisdom more than human, and suppose what they did to be beyond amendment. I knew that age well; I belonged to it and labored with it... We might as well require a man to wear the coat which fitted him when a boy, as civilized society to remain ever under the regimen of their barbarous ancestors.
--Thomas Jefferson

Our founding fathers did some brilliant work, but with the benefit of hindsight, it is clear that there is room for improvement. The framers foresaw the need to update the Constitution, and created a process for amending it, but what would it look like if it was written today? I thought it would be a fun thought experiment to write a new one. Here are some points that I've come up with so far:

• In the US Constitution, the Bill of Rights is a set of amendments. This conveys the message that these rights are an afterthought. In this constitution, the Bill of Rights will be Article I. This should include, among other things, an assurance of equal rights for same-sex and opposite-sex couples, probably by privatizing marriage, and increased protection for free speech and against censorship. The bidirectional separation of church and state must also be clearly declared.
• I think that trias politica -- the separation of power among the legislative, judicial, and executive branches -- is a very good idea, but it's clear from presidents like Dubya and Nixon that clearer limits on the branches' powers need to be defined, particularly when the branch is so centralized. In practice, the US presidency resembles a constitutional monarchy. Those powers should have additional checks, and possibly be divided among several individuals. The need for a single figurehead leader, be it a president or a prime minister, is a throwback to traditional monarchies that modern governments may be better-off without.
• No increased per-capita representation for less-populous areas. Red-staters may not like this one, but I think that the Senate and Electoral College are terribly un-democratic. Bicameral legislature is a good idea, but assigning Senators by state with no regard to population is un-democratic. With the current state of technology, there's no reason not to offer a more direct democracy, with less emphasis one outdated state boundaries, and there must be better ways to fairly represent the interests of smaller populations.
• Speaking of technology, it also creates other possibilities that would not have been feasible when the Constitution was written. Perhaps one house of Congress should have proportional representation, and there's no reason not to use instant runoff voting. It's crucial, though, to provide for protection against electronic vote fraud.
• Certain clauses, notably references to "free persons" and the three-fifths compromise, are concessions to the culture of the day an no longer hold any relevance. Many such clauses have been nullified by amendments, and such amendments should be rolled into the original version of this new constitution, but similar concessions to today's culture should be avoided where possible to create a document that would require as little amendment as possible.

Those are the points that I have thought of so far. Can you think of any others or any other nations whose constitutions with aspects that improve considerably upon that of the United States? Does anyone know of any similar projects?