Are there any good festivals in Fort Collins?

Yes! Old Town Fort Collins is a great place for festivals, especially in the summer. The New West Fest is Northern Colorado's largest free community and music festival held in August each year.
Local beers are featured at brewery festivals. There are art festivals and tours. One of my favorites is Tour de Fat which "includes an unparalleled costumed bicycle parade, New Belgium beer, eccentric entertainment, local food, unusual bike contests and much more."