Mentchlichkeit

-Someone spends many hours preparing for a shiur and delivers it.  He finds out that someone else heard his shiur and delivered it without crediting him and is hurt. 

-Someone spends many hours preparing for a shiur and as soon as he gives it, he puts it up online so that others can use it for their own audiences.  He is happy to enable others to benefit from his work.

-Someone writes a poem.  Someone else submits it to a contest under their own name.

-Someone pays an architect a lot of money to design a house.  A wealthy person, who is building a house two houses over, calls and asks whether they can use the blueprints to build the identical house.  This is without offering to pay anything.  The person gives them the blueprints while thinking it was quite a chutzpa to have asked for it gratis.

-Someone buys a stunning accessory to wear with her dress.  A relative asks her where she bought it and she tells her.  The relative buys the identical accessory and they both regularly show up at the same simchas wearing the same thing.

-A kalla find a beautiful outfit, a sample piece, and has it customized to her specifications.  Someone in her circle sees it and copies it and shows it up wearing it, just like her.

-A person bakes delicious cookies and is asked for the recipe.  She declines to give it because if she does, then she won't be the only who knows how to make these cookies.  They are her specialty.

-A woman shows up at a wedding wearing the same gown as one of the wedding party and a member of the wedding party tells her, in no uncertain terms, to go home and change.

-A creative person designs unique shalach manos and others copy it.

-A new minyan is started that siphons off people from an existing shul.

-There is a shiur that takes place which is well attended.  Someone in the neighborhood decides to start another shiur and this takes away people from the first shiur.

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When do you say, "zeh neheneh, v'zeh lo choser" (this one benefits and the other one does not lose out)?

How should copying clothes, decorations, etc. be regarded - as complimentary or a chutzpa?

When does geneivas daas apply? Must everything be credited to the originator?

There are halachos of hasagas gevul - of not being allowed to encroach by, for example, opening an identical type of store in an area which cannot support them both.  From what I've learned, this generally does not apply to Torah, though perhaps it depends on the circumstances.

In some of these cases, there may not be an outright right or wrong, but perhaps that is where the mitzvah "You shall do that which is right and proper (haYashar v'haTov)" [Devorim 6:18] comes in.

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This is something to think about when we are the person who is being asked for something or copied, and it is something to think about when we want to ask for something or copy someone else.  Be forewarned, people have strong feelings on this subject!