We discuss algebraic and representation theoretic structures in braided tensor categories C which obey certain finiteness conditions. A lot of interesting structure of such a category is encoded in a Hopf algebra H in C. In particular, the Hopf algebra H gives rise to representations of the modular group SL(2,ℤ) on various morphism spaces. We also explain how every symmetric special Frobenius algebra in a semisimple modular category provides additional structure related to these representations.