Is there any way to write a script to identify and mass-tag all my files with the %totaltracks% field? I'm not sure how I'd make it count the files with the same album title (and preferably, make it specific to each disc in the case of multiple disc albums).

Select all your files, open the Properties dialog, right-click, and chose "Auto Track Number".

Note that albums are grouped by directories.

Perfect, I didn't realize that set totaltracks. Thanks.