If you have a large amount of paper documents to scan on a flatbed, an automatic document feeder attachment can certainly help you to speed up the process by letting you to scan up to 50 sheets per session. Document feeders can cost up to $200 and you should make sure it fits your scanner before purchasing it.
Another option is purchasing a scanner that is designed to convert paper documents to digital files. like the NeatDesk system. Portable document scanners like the Fujitsu ScanSnap and the Pentax DSMobile 600 are also good alternatives here.
Scanning documents with your smartphone is another option. A business owner could take a picture of a receipt and use a smartphone app such as the CamScanner Phone PDF creater that will create a PDF of the image.
After digitizing your accounting documents you will want a safe location to store the documents and have the ability to collaborate on them at any time with your bookkeeper or accountant. LedgerDocs is an online document management system that will allow you to do all of this and more. You can easily upload all digital accounting documents within the LedgerDocs web application, upload via your email client such as MS Outlook and even directly from your phone once you have taken a picture of it.