<p><a href="https://3dprinting.stackexchange.com/questions/413/methods-for-smoothing-3d-objects">Methods for smoothing 3D objects</a></p>

<p>So... maybe one day it becomes community wiki. I think that we need this type of questions, so we can provide more detailed answers to methods and practices.</p>

"is still too broad?"
is answered by your own question,
"we can provide more detailed answers"
.
The problem essentially is that this Q&A format isn't suited to very long treatises on this type of subject.  It's far better to ask a specific question such as
"How do I smooth this ABS print to eliminate all signs that it was 3D printed?"
and receive several good answers, than to have a one-stop-wiki question that attempts (and usually does very poorly) at holding all the answers to all the possible smoothing questions.
So I'd recommend we leave this question closed and let people start more specific questions as they run into actual problems.