I go the lazy route...I use Shoeboxed and pay the $30 a month for them to automatically send me a "magic blue envelope". I used to intend to scan and organize everything but within a couple years I had accumulated an entire box of crap. So every month I would send off a blue envelope of the current receipts plus some of the old ones. I finally tossed that empty box a couple months ago!
I used to never even open Shoeboxed, just knowing it was there was enough. But I realized I could put my husband to work on it...so every quarter he sits at the computer with my taxes spreadsheet and matches every item. It's a strangely good feeling to know everything is ready if I get audited.