The Bible says in Philippians, "Finally, brethren, whatsoever things are pure, whatsoever things are noble, whatsoever things are lovely, think on these things."
You can apply these criteria to what you're watching, reading, and hearing. Is your choice of entertainment elevating? Is it noble? Is it true? These are some of the measures that Paul applies in Philippians about how we determine what to think about. He says, "Think on these things."
When we follow this as a guideline, we're more likely to choose activities that nurture the fruits of the spirit. And the bottom line is always, "What would Jesus do?" What would He watch, what would He read, and what would He listen to? These are very good questions to ask in every situation. A Christian is a follower of Christ, so His example should be foremost in our minds and hearts. The only way to really find that out is to study your Bible.
And as a final caution, don't be deceived simply by things called Christian or family entertainment. For instance, the Left Behind books and films are not only filled with misleading errors, they have violence.
You can apply this to popular Christian rock and similar popular Christian culture. There is a reason why much of these types of entertainments are on the rise, and I don't think God has very much to do with them.