If you already know about this, forgive my late-to-the-party enthusiasm, but Google's movie search is fantastic.
Want to know what's playing? Go to Google and type in "movie: " and your ZIP code. Here, for example, is what's playing today near everybody's hometown. You can sort this list by theater, or by movie.
You can search for a particular movie with, for example, "movie: Hotel Rwanda 19063." And you can scope out the reviews for a movie by typing, say, "movie: Hotel Rwanda reviews." Not as expansive as rottentomatoes.com, but a good bit more user friendly if you know what you're looking for.
Moviefone suddenly seems incredibly 20th-century.