Hector Molina, Catholic apologist, talks about the dangers of divination (the practice of seeking knowledge of future events or hidden (occult) things from supernatural sources) in this great article from Catholic Answers.
Divination includes practices such as ouija boards, horoscopes, tarot cards, fortune telling and even tea leaf reading!
As Hector says, divination 'seeks to circumvent God's plan and obtain answers to our questions by consulting spirits, which are in fact demonic and sinister spirits hell-bent on deceiving and harming us.'
If that isn't enough of a warning then I don't know what is! Click this link to read the full article: http://www.catholic.com/blog/hector-molina/ouija-believe-it