Thin film magnetoresistive sensors (MR sensors) are widely used in various applications. The most important are their applications as read heads. MR sensors are also used as mechanical transducers and of course as magnetic field sensors, for example in compasses. There is a large variety of MR sensors on offer in the marketplace. However, market availability of MR sensors does not mean that the research in this field is less intensive. At scientific conferences devoted to magnetic sensors or to magnetism in general the subject of 'magnetoresistance5 is covered in a large number of papers. Every year, each conference brings revolutionary news.