Indeed. Judicial review for constitutionality is itself not explicitly in the Constitution, but a power taken (usurped?) for itself by the Supreme Court. My own view is that a referendum process should exist to allow these decisions to be overturned. I suspect cases such as /Kelo/ would have been reversed by such referenda.
Forced nonincumbancy would be another interesting check-and-balance. This would not be term limits per se, but rather a requirement for all elected officials (save for the President, perhaps), upon ending their term, to /return to their home districts and reside therein/ before being eligible for the next election. I.e. appointment to a cabinet post would not be sufficient, one would have to return to one's own district