The National Constitution Center has just released its Interactive Constitution, which has (1) short essays from constitutional law experts describing how the Supreme Court has interpreted each constitutional provision, and (2) discussions of some big questions related to each provision.
The center has tried (and, I think, largely succeeded) to provide a balanced presentation: The experts were chosen with the help of leaders of the American Constitution Society and the Federalist Society. Generally speaking, and especially for the controversial provisions, the descriptive essays are co-written by two experts, one (generally speaking) from the left and one from the right; and then each expert adds his own thoughts in a separate essay. The results are very impressive, and I highly recommend them.
The Establishment Clause, for instance, is covered by Professor Marci Hamilton (who is generally seen as being on the left on the issue) and Professor Michael McConnell; the Free Exercise Clause by Professor Fred Gedicks and Professor Michael McConnell; the Second Amendment by Professor Adam Winkler and Professor Nelson Lund; and so on. The co-conspirators are represented, too, with Orin (and Professor Barry Friedman) on the Fourth Amendment, Randy (and Professor Louis Michael Seidman) on the Ninth Amendment, and Professor Geof Stone, with me, on the Free Speech/Press clauses.
So far the site covers the First Amendment to the 15th Amendment, minus a few parts of the 14th Amendment, but the plan is to cover the other materials soon, too. Disclosure: The contributors, including me, were paid for their contributions (though of course not for this blog post).