Bono took a night off from campaigning on aid for Africa and went back to his day job -- music -- as he sang along with a local band in a 1,000-year-old chant in the West African state of Mali. The U2 frontman, on a six-nation Africa tour, dropped in last night (May 22) with some aides at the Piroge bar and restaurant on the banks of the Niger River in the Mali capital Bamako.