When developing new applications and services in any knowledge domain it is essential for user interfaces to be simple and easy to use for all, including the differently-abled. The spread of mobile networks and the near-universal presence of cell phones now enable access to web content anytime, anywhere and under any conditions. Furthermore, as the median age of the user population rises, new challenges emerge such as developing e-services (e-health, e-government, etc.) and integrating disadvantaged or emarginated subjects (eLearning, social networks, etc.). Accessibility and usability are crucial for removing technological barriers and bridging the digital divide.