I wanted to highlight an article from the Advice section of this site, What is included in your cruise fare? (refer to http://cruiseline.com/advice/how-to-book/before-you-book/what-is-included-in-your-cruise-fare.
The article is a start but rather than relying on secondhand information, this is a great opportunity for everyone to go to your passenger contract and READ THE FINE PRINT!
Many times we see cruise reviews containing complaints about things that would have been non-starters had the person bothered to read their passenger contract. It is never a bad time to read your contract... in fact, it is always a good time, especially prior to signing on the dotted line.