www.themoviespoiler.com has saved me hundreds of dollars.
It provides detailed recaps of pretty much every major movie released recently. It takes about 10 minutes to read a recap and then you realize that most movies out there are crap and a waste of money to see. If I see something that sounds good, I stop reading the recap before I get to the end and then go out and see it.
Just remember if you go there... it will tell you pretty much everything about the movie!
The funny thing about it is that, since I know the whole plot of the movie, I'll often reference a movie I read about in a conversation, and people will ask me "Oh, how was that movie?" and I'll have to admit I never saw it, but that I know what its about and how it ends.
The one thing I really like using it for is for those shlocky movies that are churned out constantly that promise some shocking twist or ending. (Flight Plan, Butterfly Effect, Hide and Seek, The Lake House, Don't Say a Word, etc, etc). They almost always suck, but are adverstised well to make people think they "have" to see it so they can learn the answer to the "twist" teased in the commerical. I just read it on The Movie Spoiler and then I learn the answer to the "shocking twist" without having to see the crappy movie. I can't wait until The Wicker Man is on there so I can see what that's all about, because the commericals look suspensful, but you gotta know the movie is gonna suck.
Also, I find
www.rottentomatoes.com to be the best movie review site out there.