We use a 2 part process. One is to create the expense report in our PeopleSoft system. The nice thing is that they have it directly integrated to our corporate AmEx card accounts, so all charges flow through to PS. It's a lengthy process, though, to create a report - select charges, confirm/change category, manually break out hotel bills (lodging, food, incidentals, etc.), match to billing code, download summary, submit.
Part 2 is sending over the receipts. Fortunately, we no longer have to do the manual way of taping receipts to a sheet of paper, scanning them, and faxing them over to whatever group processes them. We can now scan to whatever app, create a pdf, and email to the expense mgmt group, although the subject and message body need to contain specific information to tie to the expense report.
I've been using Smart Receipts on my Android it meets my needs.
I'm told we'll be moving to a cloud-based/SaaS finance system this year which will allow for mobile expense reporting.
So full disclosure - my admin submits all my expense reports, so I just need to send her my receipts and she does the rest. But I tried it a couple of times and it's pretty onerous.