In a summer of constant music-slash-arts festivals, only a handful cost nothing to attend. Of those, fewer are worth the bother of attending. But this weekend's three-day UmojaFest, an outdoor celebration of African-American culture and heritage, is a sizable, all-ages affair with something for just about everyone: from face-painting to hip-hop to fashion shows to parades to the outdoor market. Even if you don't live nearby, it's worth the journey just to stuff yourself with cuisine from all over the African continent (not to mention Caribbean, Creole, and American dishes). There's something wrong with you if the mere thought doesn't make your mouth water. But if you come for the food, stay for the music. With three stages to pick fromhip hop, gospel, and soulthere should always be at least one performer onstage at any given time. And Saturday's NYC-based headliner, Amanda Diva, is an incredible emcee with all the makings of another Mary J. Blige or Lauryn Hillgreat delivery, a sultry, soulful voice, and a strong message.