Allow more document identifier information
Right now you have Name, Date, Comments, and Labels. I would like the ability to add further source information about the document.
I use this to maintain a large collection of articles. It would be nice to be able to include as fields the Author and Publication Name (i.e., magazine or journal where the article was published).
BTW, I love the relational database idea (i.e., labels) rather than standard directory structure used by the other programs I've tried. However, I do miss the ability to add further source information. While I could use labels for journal name, it just isn't practical to create a label for each author.