Ubiquitous computing (UbiComp) is a more than two-decade-old phenomenon, but its impact is still evident on the design and development of various mobile and internet-based applications and systems. In this paper, we present a novel and interesting research subject concerning the need for an understanding of the design of future UbiComp technologies, specifically aimed at teenage users. Designing UbiComp technologies for teenagers and young children is quite new, so little work is reported in scientific literature. For this reason, existing literature available on the design and use of internet and handheld-based applications by teenagers and young children has been examined, since it presents crucial design level considerations that might also be applicable for designing UbiComp technologies. The contribution of this paper is as follows: 1) It presents a multidisciplinary literature review comprising of previous research on child-computer interaction and various other Internet and media-based studies involving teen users. 2) It presents a new research agenda governing the design and development of UbiComp and 'cool UbiComp'. 3) It outlines some of the interesting experiences from our ongoing field studies in India involving school-going teenagers. 4) It gives detailed discussions on various associated ethical issues concerning the process of approval needed for involving teenagers in the research, and practiced protocol for ensuring various international ethical standards and norms during our field studies in India. 5) It presents four crucial challenges on 'designing for teenagers' concerning privacy in teen design, social implications of technology use by teenagers, lack of education on ICT and internet safety policies and missing psychological and sociological foundations of designing for teenagers.