His songs have been covered by artists including George Strait, Joe Ely, Lyle Lovett, The Highwaymen and Nanci Griffith.

Keen was a fan of the British rock band Cream, and was influenced by country music from artists Willie Nelson, Norman Blake, Jesse Winchester, Flatt and Scruggs, Bill Withers, Gary Stewart, and Jimmie Rodgers.

[7] He performed in nightclubs and live music venues in Austin, including Cactus Cafe, Emma Joe's, Alamo Lounge and Liberty Lunch, Anderson Fair in Houston, and Gruene Hall in New Braunfels.

[18] His 1997 album, Picnic, marked the beginning of his on-again, off-again relationship with major labels (both that album and 1998's Walking Distance were issued on Arista Records, and 2001's Gravitational Forces, 2009's The Rose Hotel and 2011's Ready for Confetti were released on Lost Highway Records).

The producers with whom he has worked on those albums have included John Keane, Gurf Morlix, Gary Velletri, and Lloyd Maines.

Keen covered all of his own expenses for travel and only wanted to show a token of his gratitude to a fan who made the ultimate sacrifice for his country.

[citation needed] In January 2022, Keen announced that he would stop touring and performing publicly after September 2022.