I'd like to see a web site like www.imdb.com but instead of being
about movies, it would be about all US politicians. You'd be able to
to get basic info about who represents you, upcoming elections, et
cetera.

You could search for a politician and check how (s)he has voted on
certain issues. There could also be links to any relevant articles
about them, editorials, etc.

(added by me, Steve Quezadas): Perhaps make the site editable like
Wikipedia?