In my projects I often work on multiple related files that are stored under different directories, so when time comes to commit update or tag, I have to go to each individual directory and commit one file at a time. The feature I would want is an ability to add multiple related items to a named Batch (similar to a playlist in MP3 player) and when the time comes, commit entire batch at once. I invision this behaving like a context menu item that has an option "Add to Batch" and then gives you a prompt to select existing batch by name or to create a new one. As far as storing batches, that could be made into a file that is associated with TortoiseCVS and provides context menu to Commit, Tag, Update, etc.
You do realize that you can just select Commit on the top-level directory and then choose which files you want to commit, right?