  We show that the semigroup of real linear fractional transformations on a
proper subinterval of the real line does not admit any 2-generator dense
subsemigroups, and then we construct a 3-parameter family of examples of
3-generator dense subsemigroups. We also construct an explicit example of a
2-generator dense subsemigroup of $2\times 2$ real matrices. In the complex
case, we prove the existence of uncountably many 2-generator dense
subsemigroups.
