Seriously? Try searching for "radio" or "radio tuner" in the app store.
Popular apps include Wunder Radio, Tuner Internet Radio, and TuneIn Radio. These have hundreds of stations preloaded and you can usually add other stations.
Additionally, many stations have their own apps - KEXP, KCRW, etc. Search for the specific station. There's also a Public Radio app that works for most NPR stations in the US>