Appraising the benefits of new technologies is a commonly accepted challenge for any organisation and is a prime area for technology management research. As the future potential of any technology is always associated with some level of uncertainty it is thus important to either reduce or better understand this uncertainty in order to make appropriate business decisions. A wide variety of methods are available that intend to service this need, such as net present value calculations, real options, portfolio methods, road-mapping, expert systems, etc. Technology companies often use a selection of or hybrid models. The problem is thus inherently interdisciplinary. The techniques used to appraise new technologies range from �hard� mathematics, often taken from the finance sector, to more �softer� techniques that enable people to systematically structure the potential outcomes and their underlying uncertainty. Furthermore, the use or purpose of the techniques can vary as well. Methods can be applied to justify decisions and judgements made, but also to support the process of shaping this judgement, or to provide boundary conditions and hence enable the decision making process. This paper aims to provide an overview of prevailing methods and tools and evaluate their relative value in the process of business appraisals. We will elaborate on the overlaps and gaps and conclude with recommendations for future research.