You automatically convert questions with more than 30 answers to CW (community wiki), then, reputation will not be given to the main person who made the answer. I have seen answers with more than 300 upvotes for a person with 150 rep, he didn't profit from his effort because of this problem. This may keep people from answering very common questions if they know this!
I am so sorry for the bad expression, but it is not fair IMHO!
For example:
Create Excel (.XLS and .XLSX) file from C#
The only fault of "Peter Majeed", "Jan Källman", "Panos" is that the question has 31 answers!!! it is not fair at all, for example the user jan kallman have only 151 rep, his answer has not changed by others, his answer has 138 up-votes only (1380 reps), he benefits only from 15 of them (150 reps only)!! if the question has 29 answers, he will benifits from them all, I think this should be mentioned seriously.
* EDIT *
I am not objecting to converting the questions to community wiki, I am objecting to not give the reputations to their owners!
Ok, what about this question:
https://stackoverflow.com/questions/477748/what-are-the-best-c-sharp-books
This has 20 answers, why the excel question's reputations gone out, but the c# book question got all of their reps?? they are both an off-topic questions!
What about this??
For example: Mike Polen's answer has 456 up-votes, he didn't got except a a little of them!!
* EDIT *
This is what @Pekka written:
@Mohammad where is the effort in that question that's supposed to be stolen away? What about that question should be worth thousands of reputation points while actual good questions that people put hours or days of effort in will usually gain 10 upvotes max?
This is the best answer IMHO, this has convinced me 100%!
Take this question and answers:
Quadrilateral Shape Finding Algorithm
This questions are worth reputation and respect! These answers won't take more than 250-400 reps with the bounty, although they worth more, but my previous examples wouldn't bring any rep compared with the last one!