Would have to dig into my comments on Yahoo group to recall - but Berchemia discolor, Canarium schweinfurthii, Aframomum sp., Oyster nut, Annona senegalensis and Vitex sp. springs into mind. There are many more which I have never tasted, but they are (even more) highly recommended so the Ugandan list alone is a lot longer of course. Several others are still good, but perhaps not to that level; Tamarind, Cordia sp., Chrysophyllum sp., Pseudospondias microcarpa, Giant Yellow Mulberry etc.
I think the main problem is accessibility together with lack of cultivation and selection practices here in Africa - in addition; most people are not less interested in trying new things; as an example I have traded more soursop and noni seeds than rare African species...