In a VBA module in excel 2007, is it possible to call a web service? If so, any code snippets? How would I add the web reference?
Yes You Can!
I worked on a project that did that (see comment). Unfortunately no code samples from that one, but googling revealed these:
How you can integrate data from several Web services using Excel and VBA
STEP BY STEP: Consuming Web Services through VBA (Excel or Word)