I copied the materials formula for glass I found here
http://en.wikibooks.org/wiki/Blender_3D:_Noob_to_Pro/Every_Material_Known_to_Man
but it turned out opaque (turned on raytracing). Do you know what’ s wrong? http://www.ceeteesoft.com/glass.blend
In Mirror Transparency, turn on the ZTransp button and move the fresnel slider up a bit … adjust to taste 
Render and notice that you can now see through the cube.
Hope this helped.
Edit: By the way, you don’t have to have raytracing turned on. The internal renderer can render your glass transparant.
Got that working now. Is there any way I can save material settings to reuse? The ‘F’ button for saving the datablock doesn’t bring up any dialog so I guess that’s something else.
The F-Button saves the datablock even if there is no real user of that datablock (F for fake-user)
you can import your material from another blendfile with Shift-F1 as you can import any other object
if you save all your materials in one special blend-file you have a material-library like
http://www.free-webspace.biz/sonix/Cars/Blender234CarMaterialLibraryR1.html
regards
No time to read all posts but after downloading the .blend file I saw that ray-transp and ray-mirror were off. They need to be on.
No, they don’t. You really should read the above posts.