Fractal objects can sustain strongly localized optical modes with high quality-factor. Intense local fields associated with the dipolar eigenmodes in fractals ultimately result in significant enhancement of a number of optical effects. In particular, such basic optical processes as Rayleigh and Raman scattering, degenerate four-wave mixing and harmonic generation, two-photon absorption and non-linear photoemission can be enhanced by several orders of magnitude in small-particle fractal composites and self-affine films.