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.