Film falls into the realm of communication, so write a your thesis on something related to film. For example, have your thesis deal with the portrayal of women in popular movies of the 1940s. Focus on two or three well known movies so you narrow your scope of research, otherwise you have too much material to work with. Another example is to study the political implications of a modern movie, like "Avatar," and what it is saying about the political environment in the United States.
Video games are played in all forms by people all over the United States. Write your thesis about video games and their effect on society. For example, you may explore whether first person shooting games encourage players to shoot in real life. Another idea would examine whether video games can cause people to become violent.
Ethnicity appears in all forms of media and communications. You can write your thesis on how African American and Hispanic characters are portrayed in anything from film, books, magazines, music and advertising. For example, study the differences between magazines that are read by primarily Hispanics and magazines with a white readership. Or, look at how many movies star white characters as opposed to minorities.
Social media is a rapidly growing way to connect people, so write your thesis about it. Many people use social media as a way to advertise and further their businesses, so write your thesis on if it is more effective than traditional forms of advertising. You can also study how different age groups use social media.
Write your thesis about how a certain group of people were portrayed in the media during a specific time period. You can compare it to today or just leave it as an in-depth period study. For example, you could study how Italians were represented in the media during Al Capone's reign in Chicago. Question whether the were Italians looked up to or feared. Examine whether you could compare them to modern day mobsters.
This is a topic that offers all kinds of thesis ideas from all over the world. You can look at Germany's use of propaganda during World War II and compare it to America's, or just look at the effect that the propaganda had on Germans. Look at how America's propaganda and the use of Rosie the Riveter helped change the cultural climate and how women were viewed.
For your thesis, examine whether cell phones and text messages have made people terrible spellers because everything has to fit in a short amount of characters. Also, you can see how cell phones have changed the way people communicate overall. Cell phones provide many different avenues for you to write your thesis on.