Greenawalt has worked with Iggy Pop, Rufus Wainwright, Nils Lofgren, The Pierces, Ben Kweller, Ric Ocasek, Branford Marsalis, Joe Strummer, Philip Glass and many others.

In 1980 Greenawalt formed the "Sarcastic Post Punk No Wave Death Disco" band The Dark who, after gaining a loyal East Coast following, drew the interest of Ric Ocasek, lead singer and guitarist of The Cars.

[3] Over the last 30 years, Greenawalt has produced a wide variety of music, including records by bands such as Nils Lofgren, Ben Kweller, The Pierces, Eve's Plum, Anya Marina, Iggy Pop, Nellie McKay, Julian Velard and Eric Hutchinson.

Since then, Greenawalt has performed the marathon show three more times at Brooklyn Bowl and three years running at SXSW in Austin, Texas (2010,[4] 2011).

Performers at these various concerts have included Nellie McKay, The Naked Brothers Band, The Pierces, Adam Green, Ryan Miller of Guster, Jeremiah Birnbaum, and Freedy Johnston.