Another weird and wonderful bird!
The Red-billed Oxpecker (Buphagus erythrorhynchus) is native to sub-Saharan Africa, and are most often found on the backs of large grazing animals. The Red-billed Oxpecker seems to do all the benefiting in this relationship (although there is debate among scientists on this matter). They eat ticks and fleas that they find on the animals they perch on. Oxpeckers also feed on the blood of their chauffeurs by opening up existing wounds. Oh, and they use hairs plucked from larger animals to line their nests.
They kind of sound like jerks to me, but they sure are colourful!
Reference photos can be found here, here and here.