I wrote about this a couple of times. I use a service called Shoeboxed (http://littlebitofcode.com/2011/05/05/netflix-for-documents) that will scan your receipts and documents for $20/month. Works like Netflix, they send you envelopes, you fill them up, they scan them. I use them for receipts.

I also use a NeatWorks document scanner (http://littlebitofcode.com/2010/02/15/getting-receipts-and-m...) that I've been really happy with. I use it for documents. The combination of the packages has perfectly fit my needs.