In this lightning talk presentation from the 28C3 conference, the zunkworks crew outlines their work using simple RF hardware and a Linux laptop with soundcard to experiment with Radio Direction Finding (RDF). RDF has long been used in commercial and public safety activites, and the approach employed here attempts to bring RDF development down to a practical, affordable level for the average radio experimenter.
Project details can be found on the zunkworks RDF page and you can view the PDF of the 28C3 presentation slides here.
good project to do and study!