Paperpile is great for PDFs in that you can easily see which items are missing PDFs, you can quickly re-attempt download of PDFs when at work, etc. However, about 40% of my items are books and these features don’t work so well for books.
I propose adding an “on shelf” tag and filter that will make it easy to know which books I have and which ones I need, just like I can do with PDFs.
Even better would be if, for those that I need, if I could easily look up whether they are available as eBooks or, if not, whether they are in a nearby library (maybe with a WorldCat lookup?).
And when the mobile app is out, one could use the camera to scan the barcode of a book to add it to one’s shelf, automatically changing the status of the item if it is already in Paperpile.
These last two suggestions (worldcat lookup and barcode scanning) are just to point out how an “on shelf” tag could be made even more useful, but being able to easily filter books the way one can with PDFs would already be very helpful.