Reports of rappers engaging in charitable endeavors usually revolve around tales of Jay-Z and Nas giving out a few free Thanksgiving turkeys to residents of their former housing projects. But the Bay Area's Zion I and the Grouch are taking an authentic grassroots approach to the idea of effecting social change through music by donating a percentage of profits from each of their 19 shows on the Heroes in the Healing of the Nation tour to a hand-picked local charity. Underscoring the venture's legitimacy, the gesture is being facilitated by the Air Traffic Control nonprofit, which worked with rock band My Morning Jacket on a similarly philanthropic campaign. And proving conscientious rap music doesn't have to be po-faced and self-righteous, the duo's just-released album positively bumps.