I know a lot of us know about
www.imdb.com already, but for those who don't, it's the ultimate movie database. Get all the info you want from the latest blockbuster to your favorite Edison experimental film from 1890. Has ratings, reviews, cast information, years, etc.
www.rateyourmusic.com is the best music community online. For those of us who love music and still appreciates the album as an art form, this site's a must. Again, any artist and album you can think of has a page with ratings, reviews, etc. All-time and yearly rankings a-plenty to agree or argue with.