Changing default applications, for developers

When not using those uber-featured desktop environments (such as KDE or Gnome) out there, it can sometimes be challenging to find a simple, text-based way of configuring things. For example, I am currently writing a GTK2 program, which uses the method gtk_show_uri to open files using default programs: on the computer I am using at work, this results in opening Acrobat Reader over an XDMCP connection, which is really distasteful. Even using GNOME’s control center, there does not seem to be a way to change that. What should I look at?