Is there any way to view the contents of the solution user options file (the .suo file that accompanies solution files)?
I know it's basically formatted as a file system within the file, but I'd like to be able to view the contents so that I can figure out which aspects of my solution and customizations are causing it grow very large over time.
The .SUO file is effectively disposable. If it's getting too large, just delete it. Visual Studio will create a fresh one.
If you do want to go poking around in it, it looks like an OLE Compound Document File. You should be able to use the StgOpenStorage function to get hold of an IStorage pointer.