In user shops, we have the option to view the items in there on the basis of the item's use (books, clothing, food, etc). However, there is a fair chunk of items which have no standard use, and so can't be viewed as a separate group. They can only be seen when mixed in with everything else. Would it be possible to get a categorisation for "no use" items?

Yes please, especially since categorization is spotty at best.

I don't ever really sort by categories but this would be nice. More sorting options are always welcome.