We demonstrate specular reflection of a thermal rubidium beam with low-power laser light. The atoms are reflected by the gradient force of an evanescent wave enhanced by surface plasmons excited in a thin silver layer. With only 6 mW of diode laser power we achieve a deflection angle of 2.5 mrad. Analysis of the velocity distribution of the reflected atoms yields an enhancement factor of 60 +/- 20 for the amplitude square of the evanescent wave.