91.3 is one of the best radio stations in the city, by far. And few other cities have a station like it. WYEP is a great place to go for new music that doesn't fall into the mainstream scene. They play a lot of bands and artists that are still coming up, as well as a good collection of older quality music. Dylan, The Band, etc to My Morning Jacket, Cold War Kids and more.
The station also has plenty of free concerts throughout the summer, bringing new and growing acts to the city. Fitz and the Tantrums just rocked a show between Jukebox the Ghost and Eli "Paperboy" Reed at WYEP's annual summer music festival. You can even go down to their studio to catch a show by bands they bring in, and they usually have some free beers from local breweries.
Overall, WYEP is just a great station and a great part of the city.