Question: In [a recent question](https://mathematica.stackexchange.com/q/297/34) there were many answers that just consisted of links to packages.
The answers, while potentially useful to the OP, contained no discussion about how these packages could be used to address the specific problem given in the body of the question.1 

So my questions are:

* When is it acceptable to post an answer that consists primarily of links?
* When are these link dumps better as comments?
* I understand that link dumps can sometimes be useful and appropriate. In these cases, how are they best presented?

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1 However, all of the packages did address the title of the question, which did not quite reflect the body of the question.

Answer: 
One obvious problem with answering questions with only a link is that links can change. This is the biggest reason I opted to delete my question on looking for a good Mathematica Quick Reference. The question itself was only really answerable with a link.

That being said, there are some links that are semi-permanent. Mathematica documentation comes to mind. However, I don't think it suffices to answer a question with only a link to the documentation. 

If a link happens to be the only way to answer a question, it probably isn't a good question for the site.
[Is it okay to answer a Stack Overflow question with a link?](https://meta.stackexchange.com/questions/13369/is-it-okay-to-answer-a-stackoverflow-question-with-a-link)

(Ironic to essentially say that one shouldn't answer with a link by posting just a link?)