How can the story "A Sound of Thunder" by Rad Bradbury be applied to the modern world?

This is an interesting question, as we don't have the capacity for time travel in the modern world. But Bradbury does have two points to make that are applicable to today. First, one main concept in the story is that very small actions can have an enormous impact on history. Eckels steps on a butterfly in the Dinosaur Age and returns home to discover that a brutal dictatorial type named Deutscher has become president of the United States. This principal of the importance of small actions can be applied to elections today: very small margins can make a huge difference. A few people deciding not to vote—or to vote—can alter world history by changing who gets into power. It can feel as inconsequential as stepping on a butterfly not to vote, but that decision can have huge ramifications for the future of the planet.
Second, as is often the case with Bradbury, a point he makes in this story is that we should treat technology with respect and not use it as a play toy. Eckels is a spoiled rich man who can afford a frivolous safari back in time to kill a T-Rex. He uses time travel for thrill seeking. Bradbury shows that using serious technology for such silly indulgences can have serious consequences. One place where technology could easily be misused today is in altering DNA. One rich person's "designer baby" could turn into everybody else's nightmare if we are not responsible about how we alter genes that get passed on from generation to generation.