This policy is now in effect, with 13 votes in favor and 2 against. In addition, three of the amendments suggested in comments passed as well. The new policy on 'topic of research' questions is as follows:
POLICY: Thesis topic questions are only within site scope if the asker requests feedback about a specific proposed topic. Questions like “What would be a good topic?” will be deemed to be general and unfocused and therefore will be closed. The OP has the option of requesting a reopening of the question if it is modified as per the above policy
A special exception can be made for specific programming-style projects on a specific topic, or requests for ideas for implementation, along the lines of this question.
When closing a question using this policy as the basis, please link to this discussion.
From time to time, someone posts a question requesting advice on choosing a research project. This might be a project for a class, a Master's Thesis, or even the focus of a doctoral dissertation. We believe the best resources to consult are your course instructor, teaching assistants, and thesis advisor. They can provide better, more in-depth, advice than brief answers on a web site. For anyone who would like to ask such questions here anyway, please be aware of the following policy:
POLICY: Thesis topic questions are only within site scope if the asker requests feedback about a specific proposed topic. General, unfocused questions like, "What would be a good topic?" will be closed as off topic.
One of the objectives of this site is, "Knowledge sharing, not shirking." An essential part of research is to brainstorm project ideas that may or may not be sound, so it is reasonable to use this site to ask for feedback about a project idea you thought up but have not thoroughly investigated. On the other hand, if a project (or thesis) is supposed to be yours, it is inappropriate to leave all the conceptual work to others.
Update: Note that there are now suggested modifications to the policy in the answers. Please vote on them as well (the same rule applies for adoption).