During the past two years, the Scientist's Expert Assistant (SEA) team has been prototyping proposal development tools for the Hubble Space Telescope in an effort to demonstrate the role of software in reducing support costs for the Next Generation Space Telescope (NGST). This effort has been a success. The Hubble Space Telescope has adopted two SEA prototype tools, the Exposure Time Calculator and Visual Target Tuner, for operational use. The Space Telescope Science Institute is building a new set of observing tools based on SEA technology. These tools will hopefully be foundation that is easily adaptable to other observatories including NGST. The SEA project has aggressively pursued the latest software technologies including Java, distributed computing, XML, Web distribution, and expert systems. Some technology experiments proved to be dead ends, while other technologies were unexpectedly beneficial. We have also worked with other projects to foster collaboration between the various observing tool programs. In two years, we have learned a great deal that will be useful to future software tool efforts. In this presentation, we will discuss the lessons that we've learned during the development and evaluation of the SEA. We will also discuss future directions for the project.