Here we present the components and objectives of Dicta-Sign, a three-year FP7 ICT project that aims to improve the state of web-based communication for Deaf people by allowing the use of sign language in various human-computer interaction scenarios. The project researches and develops recognition and synthesis engines for sign languages at a level of detail necessary for recognising and generating authentic signing. In this context, Dicta-Sign aims at developing several technologies demonstrated via a sign language-aware Web 2.0, combining work from the fields of sign language recognition, sign language animation via avatars, sign language linguistics, and machine translation, with the goal to allow Deaf users to make, edit, and review avatar-based sign language contributions online, similar to the way people nowadays make text-based contributions on the Web. Dicta-Sign supports four European sign languages: Greek. British, German, and French Sign Language and differs from previous work in that it aims to integrate tightly recognition, animation, and machine translation. All these components are informed by appropriate linguistic models from the ground up, including lexical and grammar modelling, manual and non-manual features.