I think The Night Circus made the circus cool and marketable and put it on everyone's publishing radar. Here are some YA circus themed books:
-A traveling wonder show that travels from circus to circus to attract attendees into their human curiosities show.
-A girl joins a circus in search of her mother
-A group of misfits are trapped in a Victorian sideshow
-Features a circus of magic and a character who joins the circus and becomes its rising star.
Have you noticed any other circus themes showing up in books?