In nature, spatio-temporal patterns in excitable media occur in seemingly unlimited variety. As early as 1946 Wiener and Rosenblueth [WR46] introduced the concept of excitable media to explain the propagation of electrical excitation fronts in the heart. Waves of electrical activity in the heart muscle assist its rhythmic contractions. The presence of spiral waves can indicate dangerous fibrillation. This is one of the motivations why the dynamics and control of spiral waves are studied. Furthermore spiral waves are typical, almost ubiquitous, patterns in excitable media; see [ZE06] in this volume. Mathematically, self-organized spiral patterns are a striking phenomenon of reaction-diffusion systems, in its own right, motivated by a large variety of application areas.Slime mold aggregation is another example. As long as food in form of bacteria is present the slime mold cells live independently in the soil. As food becomes rare they form a multicellular "organism". This "organism" moves in order to find appropriate conditions for production and dispersal of spores. During the early phase of aggregation, chemotactic movement can proceed in form of spiral waves [FL98].Spiral waves also arise in the oxidation of carbon-monoxide on platinum surfaces [BM03]. In 1972 they have been dicovered by Winfree [Win72] in the photosensitive Belousov-Zhabotinsky (BZ) reaction, see for recent investigations for example [ZBB + 03, ZBB + 04, ZE04]. Both reactions are studied in the SFB 555. The classical BZ reaction is a catalytic oxidation of malonic acid, using bromate in an acidic environment. Experimentally it exhibits well reproducible drift, meander and "chaotic" motions of the spiral wave and its tip.In several experiments and numerical simulations, transitions from rigidly rotating spiral waves to other more complicated waves have been observed. The dynamics near rigidly rotating waves and their transition to meandering and drifting spirals has been studied extensively; see, for instance