Receipts, what are they good for?

Seriously. What are receipts good for besides:

1) Letting you return stuff
2) Helping you track things for tax purposes
3) Expense reports
4) Reminding you how much money you waste

?

I'll admit it - I'm a receipt-addict. I have to keep all receipts that I get. Even when there are no receipts to give (like the guys on the corner carts in NYC selling bagels for $1.00), I ask for one, usually resulting in the guy in the cart cursing me under his breath as he scribbles something unintelligible on a scrap piece of paper. It makes me feel better, though, to have that scrap piece of paper. It's a receipt goddammit.

That being said, I'm trying to streamline my life. I want to eliminate clutter and excess. That means paring down my wardrobe, throwing away or donating items I don't use anymore. It means trying to keep my paper records to a minimum - only the important docs stay (usually meaning things related to taxes or anything else that can get you fined or thrown in jail).

So something has to be done with my receipt collection. I still have boxes of receipts from 1992, back when my big spending consisted of a bucket of popcorn on my once-monthly movie outing.

My current plans are to, moving forward:

1) Throw away all credit card receipts related to food or services received after matching to my credit card statement
2) Keep all receipts that may have tax implications (e.g. medical bills, moving expenses, unreimbursed job related expenses)

But I have a feeling that I might be missing something. There must be a reason why Roy Rogers gives you a receipt for a combo meal, other than the off chance you are on business, right? Or is that the sole reason why so many places have the "if you don't get a receipt with this order, your meal is free" policy?