Don't have one. But what's yours (dare I ask)?
Not sure it should be limited to just one. Perhaps the logo should be flexible enough to allow for a rotating or random tagline.
I was thinking something along the lines of "Jazzfanz: glass half full, half empty, and half stupid."
"Jazzfanz: keeping PKM off the streets".
"Jazzfanz do it with rhythm"
"I know, I know, it's serious"