Crossmedia systems are becoming the trend due to technological advances, better interfaces design, and changes in user habits. Due to the use of different devices as part of the same crossmedia system, which allow supporting a multiplicity of contexts of use, useful when considering learning scenarios, new research opportunities and challenges have arisen in the design of these systems. This chapter addresses the effective design of crossmedia systems and interfaces with a particular emphasis on iTV, PC, and mobile devices, through the eiTV application, designed and developed to illustrate and explore this paradigm, based on cognitive and affective aspects that influence user experience. The eiTV application is capable to create, access, and share personalized informal learning environments (created as additional information to the video being watched), via iTV, PC, and mobile devices (the preferred or most adequate device in each context of use).