Muldoon has contributed the librettos for four operas by Daron Hagen: "Shining Brow" (1992), "Vera of Las Vegas" (1996), "Bandanna" (1998), and "The Antient Concert" (2005). His interests have not only included libretto, but the rock lyric as well, penning lines for the band The Handsome Family as well as Warren Zevon whose title track "My Ride's Here" belongs to a Muldoon collaboration. Muldoon also writes lyrics for (and plays "rudimentary" rhythm guitar in) his own Princeton-based rock bands. Rackett (2004–2010) was disbanded in 2010. Another of Muldoon's bands, Wayside Shrines, has recorded and released thirteen of the lyrics included in Muldoon's collection of rock lyrics, Word on the Street. His current group is known as Rogue Oliphant.