Love this idea!
Here a use case:
On every business travel I have to register every expense, categorize them (airfare, business meals, lodging, rental car, transportation, misc. expenses, misc. travel, etc.), add justification/description, attach a receipt (picture, scan, pdf, etc.), and specify if there are any personal items on that receipt as well (in case that could not be paid separately).
It would be really good and a hughe timesaver, if you would be able to specify that right away, and export a full report once you arrived back home.
Export to a finance system would be nice for some, export to other formats like pdf would help even more.