Given TheDAO hack, security has become more of a focus for smart contracts. Are questions that request for an audit or analysis of smart contracts for vulnerabilities and ways to improve, on-topic?
In general I feel these questions are hardly on-topic or too broad for our site. They do not attempt to question a certain problem the user faces with her code but rather generating a general feedback loop which could lead to open discussions.
However, it might be worth to highlight and recommend the Code Review Stack Exchange site.
Code Review is a question and answer site for seeking peer review of your code.
No. The community decided to close such a question as off-topic: Please help auditing my first contract!
Other similar questions may have to be evaluated on a case-by-case basis, for example some of them may be off-topic due to being too broad, or primarily opinion-based.