Sir Thomas More's Utopia has been used as an inspiration for all types of media. More importantly, More's text has has often been used as an example in many social movement of how things ought to be.
Many people wrote about utopias long before More, but the two best known are Plato's Republic and Saint Augustine's City of God. What makes "Utopia" particularly convincing, though, is that he wrote it as if he had actually visited this place and came back to tell others about it. His description of the society includes the use of trade, how government works, family units, and even about military operations.
More also recognized that how things work isn't the only important part of a society. He took the time to address the attitude of the society when it comes to the behavior of the individual and the group.
Although the time in which More wrote this piece was much different than the time we live in now, it continues to invite the curious and the hopeful to make life better.
Because this text is out-of copyright, it is available for free from many sites. It is available as an audiobook download from Librivox.org and as text from Gutenberg.org.
Sacred Texts: Utopia Index
The City of God by Saint Augustine of Hippo