Below is some of the free software I been involved in developing over the years or have found particularly useful. Many of these programs I use frequently in my courses and research.
• Eruption!- A web-based role playing exercise requiring you to manage a volcanic crisis. The exercise is highlights the tools and techniques used in eruption prediction ands seeks to improve decision making skill.
• HydroToolBox- A free Excel plug-in that adds many useful functions for field hydrology.
• ChangeUnits - Another free Excel plug-in that greatly simplified units conversion. Unlike most unit conversion tools, ChangeUnits allows you to convert multiple units in a single step. So, for example, only one step is required to convert acre-ft/yr to m^3/s.
• GeogTools- Yet another free Excel plug-in that adds useful functions for converting between geographic coordinates, particularly (latitude, longitude) and UTM.
• GWTools- (Under development) And yet another free Excel plug-in that specialized functions commonly used in hydrogeology.
• Chart Labeler - And another free Excel plug-in that adds options for labeling data points on Excel graphs (charts).