I see some obvious options:
1. Handle as a regular question.
* One can think that most starred answer is the best one. And though usually it is safe to have that assumption in this case it's not true. Libraries can evolve (or opposite fade away) fast enough.
* New answers don't receive enough attention.
2. Create a separate type of post (unsure what should be an appropriate name for it).
* Without some kind of rate it's hard to tell what is popular choice.
3. Forbid it at all
Update: We've added a new question type 'Recommendation', please feel free to give it a test run.
Thanks for asking this, and thanks for asking it here, as I do think this is the kind of question that should be worked out community by community.
My personal preference is option (2):
> create a separate type of post
I think it's most similar to the "meta poll" post type we have elsewhere and we could just call it "poll" (or "recommendation"). The answers can be owned by the 'community' user, so no stars are earned, and (unlike meta polls), I don't think stars should be awarded for the question.
Having a separate post type means it's easy to exclude them from searches, but it keeps them 'in community' rather than having something like softwarerecs.stackexchange.com.