Discovery of GIS data is broken. It is overly complicated and incomplete. Organizations spend time and money on creation and acquisition of data, yet it sits on hard drives, dvd's, and shelves without a straightforward way for others to discover it. Discovery tools that do exist have usability issues which alienate users and prevent wide adoption. Too often, data discovery is an afterthought, grafted onto tools that have been designed for analysis, or treated as one feature among many in a map portal. Thus these tools attempt to serve every possible user need and in the process become unusable. Simply put, we need an application which enables discovery of GIS data with an emphasis on user experience, integrates seamlessly with other tools, and streamlines the use and organization of geospatial data.We present GeoBlacklight, a collaboratively designed and developed open source software focused on discovery use cases. The project builds on existing, widely adopted open source projects. GeoBlacklight fills the gap in discovery tools for geospatial data by providing a simple, yet powerful intuitive interface. To reach this goal, Stanford University embarked upon a comprehensive design process. Our process includes an environmental scan, stakeholder interviews, user interviews, inter-institutional collaboration, and rapid prototyping. We will present the user personas that have been distilled from our interviews, the user stories and feature prioritization process these inform, and prototypes of the software we have developed so far, as well as plans for future development.