VB.NET (which now has static metaprogramming and closures) + COM automation isn't too bad in my experience. You could also use Python for COM.
(I've found that when you set the application to be visible and each command is carried out visually, it's very impressive to non-programmers, especially ones who don't use macros.)
Other than that, http://poi.apache.org/ and a marginal language that targets the JVM is probably your best bet for now.
Poi has worked well for our projects where we have to export customer data to XLS (a commonly-requested feature that is almost like a checklist item)
I find the file system within a file (OLE2 compound document) fascinating. I wonder who at Microsoft came up with that idea (or was it really an idea by technical committee)
(I've found that when you set the application to be visible and each command is carried out visually, it's very impressive to non-programmers, especially ones who don't use macros.)
Other than that, http://poi.apache.org/ and a marginal language that targets the JVM is probably your best bet for now.