A list of planned and recent satellite-related observations is maintained on this IJW Satellite Discipline site.
Helmut Rucker, IJW Magnetospheres Leader, has established a Web page for the 1999 Multiwavelength Joint Observing Campaign, where observers can record their planned observations of Io and the Jupiter system in the critical year of 1999, when two close Io flybys of Io, and several additional passes through the Io torus are planned by the Galileo spacecraft. Please visit this site and record your observing plans!Galileo SSI Io Planning Page with details of Galileo's C21 - I27 observations of Io, including images showing camera fields of view superimposed on existing images. Alfred McEwen asked me to "attach a warning label that this is a working page, changing daily, as we consider and resolve many issues", so here it is.
Galileo radio occultation results for Io's ionosphere, by David Hinson and Joe Twicken at Stanford
IRTF Galileo Support Jupiter/Io Monitoring Program