Japanese anime is very popular and I've noticed that there are quite a few people who've decided to learn Japanese because of their love of anime (have a look at my language poll where I ask people about their motivation to study Japanese). The dialogue in anime is often very colloquial, so you probably won't find it in textbooks. "Japanese in Anime & Manga" is a fun site that can help you to learn expressions, which are used by typical anime characters (a boy, a girl, a scrapper, a samurai and so on). There are many quizzes and games available, too. I hope it will be useful for your studies.