The MacDoctor has been playing with an iPhone and iPad app to scan and store invoices and receipts, taking you down the route of a paperless office. The product is Piikki. Simple to you use, it allows you input from the camera, email attachments of PDF's and some flat bed scanners. It syncs with Dropbox, Google Drive and Evernote. You can tag and file receipts and invoices, password protect files and even see graphs of your spending etc.
It's beautifully designed app and a joy to use. Take a look and let us know what you think!