The main market is colorful and interesting but a little claustrophobic and cramped, definitely worth a visit if you haven't seen it. See the entry in the "Buy" section below.
The Chilunga Cultural Tourism Program (http://www.chilunga.or.tz) is run by a local NGO. They can arrange guided hikes in the hills to the south of the town, visits to local villages, and trips to Mikumi National Park. The community is directly involved in designing and organizing the cultural tours, and the income generated is used to fund development and conservation projects. Their office is on Rwegasore Street, Opposite Morogoro Hospital Main Gate, in the YWCA Campus.
HIKING CAN BE DANGEROUS without a guide; robberies/muggings are not unheard of.