Ideas
I've got to admit...Jennie's idea is great...but on the off chance you want something different...
1. Video Games and their effect on the culture in America
2. Cell Phone and Text Messaging and how that has changed the way we do things.
3. Television (you can argue just about anything from that standpoint...there is the use of children's programming in fostering education, the use of marketing in television, the move towards reality television and the desire of the everyman for their 15 minutes of fame, and SOOOO many others.)
4. Branding and the American obsession with being seen in the "right" clothing, drinking the "right" beverage, or other branding issue.
5. Media effects on human health issues (fast food, anorexia/bulimia and other eating disorders on the rise due to media protrayals, etc.)
Pretty much...sounds like the world is your oyster...find something you feel passion about and write it.