Human organs, marriage to foreigners. Interestingly, these may share the attribute of crossing the "body boundary." I'm not sure.
I'm not entirely sure I'd count either of those as products or services.
ETA: Is paying a foreigner to marry you even illegal?
Oh, here's another: Public services - you can't purchase the services of a cop or other public servant, although they are hired en mass. You just can't bribe them.
But they're not performing the services on your behalf nor giving them away for free, they're performing the services because the community is paying them to perform those services.
This would be analogous to the state hiring prostitutes with a contract to exclusively service lonely people who desperately need to get laid.
In both cases you can't hire them yourself because their services have already been purchased by somebody else (the government). It'd be like paying a used car-dealer for a car he's already accepted payment for from someone else.
Can you give away children? Like to an adoption agency or a relative? I'm pretty sure you aren't allowed to sell them as a product.
And you can't give them away as property either. That would still be slavery.
All you can do is place them in someone else's care, which isn't the same thing.
ETA: Moon rocks. Historical artifacts, like the pens used by a president to sign a bill.
What? Really? If you legally owned a moon rock, or an ancient Roman belt-buckle, or a pen once used by a president, you couldn't legally sell them?
Um, I think it's
stealing the food from the charity that's the illegal part, regardless of whether you intend to resell it or not.
If you own a can of beans, does it matter if it was given to you by a friend, purchased by you from the store, or handed out to you by a charity? If you legitimately own the can of beans (or any other food), I don't see how there would be any restriction on what you do with it regardless of how you got it.
ETA: I'm not sure it's actually illegal for charities to sell donated food either. After all, many charities run stores where they resell donated items. Why not resell surplus donated food in order to raise the money to buy the poor non-food items they need?
(Of course, there's probably no call to do that, as you wouldn't get much money from reselling second-hand food, and food is one of the main things that people need. But the fact that they don't do this doesn't necessarily mean that it's illegal to do it.)