Seems nobody is interested. Then, any suggestion for me? a plugin to work on?
You can do this a regular WordPress plugin. What features specific to BuddyPress do you need? Or get a premium theme like this: http://wordpressqa.com/instant-qa/
Any theme can be a q&a theme with some modifications to the comments.php and adding something like gravity forms to the frontend for user posting(questions). There’s other language stuff you can modify so all your verbiage is inline with Q&A terminology (instead of posts & comments replace with Questions and Answers.) Add BP layer and you’ve got a pretty nifty social Q&A site. every bp site I build has a q&A site component so you’re on the right track.
You could possibly also use Forums in such a way but I wouldn’t go that route because of how they are tied to groups.
Thanks for response!
@nahummadrid , by using posts & comments , only admin and authors can post questions. To allow visitor posting, something else is needed 
@Bowromir , Basically, I need the Q&A system play nicely with main BP features and plugins. Especially a rating sytem which can communicate between BP user stats and Q&A results, also allows the rating result to be hooked up with Achievments plugin.
Other features include the ability of allowing anybody to start a post (the qurestion), registration is not required but the offer is provided; question are sortable by category or by tag; Each question has its own permalink; Questions has a list page; Questions and Answers can be listed under user’s home page nav tab,
The premium theme Instant-QA is really nice as an independant system. But I think a lot of works still needed to tweak it working with BP user profile and multisite. So, maybe it’s better dive into BP straight?
I tried Question-and-Answer-Forum plugin, it doesn’t register the post type with BP properly so that things are not running on BP; I also tried One-Quick-Post, it could work as Q&A if remove other un-related stuffs and add a rating system, but the code seems not stable in itself, Things are not smooth even without any tweaking, so I think it not worth working on.
I think the most posible smooth model is the BP activity component? — maybe make an Activity clone, remove un-related functions, allow guest post, then, adding user stats and rating system become simple.
All my thoughts might be un-realistic because I don’t have coding experience. Hope you guys continue shading lights on….
@imjscn you’re absolutely right, “adding something like gravity forms” plugin will be needed for frontend posting by users. although it is a premium plugin, you can also find some free front-end posting plugins that may work. sorry i didn’t clarify that important detail. with frontend posting plugin all your registered members can make posts, er, questions. I’ve also connected achievements very nicely with the setup i mentioned and user stats of Q&A. I really think you could do it with MU install and a dedicated subblog to host yoru Q&A site, unless your main site is the Q&A site.
With the setup i mentioned, you can easily set up a posting form for users to start questions “with there own permalinks” since they are “posts” afterall. Questions list page is just a reworked index.php.
“user’s Q&A’s can be listed under user’s home page tab — this you can do with a plugin if your Q&A is on the main site. If on a subdomain then you can just use the author.php to list the user’s questions and answers (but answers it takes a little more tweaking)
rating system, you can use any of the top post rating plugins available. GD star plugin does good job with both “posts” and “comments/answers” <– to show best answers.
To do all you just mentioned, “registration” is going to need to be required in order to tie Question/post data to the User, with WP you can just set the comments as open to all and users will not need to be registered to answer. But IMHO I always just make everyone register quickly with just the email and name, that’s what they would be entering to comment on open commenting anyway, so why not register them as a user at that point.
your thoughts are not un-realistic at all. it’s doable and been done!
@nahummadrid , thanks for the great input! I’m going to follow the path you pointed.
I still have some question about user stats/Achievement/ratings. When QA site is on sub-blog, can those stats sync with user stats in main site?
About the QA list under uesr’s homepage– since BP can track blogs sitewide, maybe can setup a filter and register a sub-nav item to show the filted result page?
Yes, let user register at posting stage–It saves the additional trouble of allowing guest posting and easier for the listing job.
@nahummadrid , after some study around the idea you mentioned above, I got an impression that we can also manage it under custom post type. When register the type, register a user role of “Question Creator” and give it the ability to create post. Then, in blog, set “Question Creator” as default role. So, any new member can create new post under the Question type.
If this idea works, a form plugin won’t be needed. Hope I am correct on this one
Wow that’s weird I was just coming onto the site to request a review for this premium plug in:
http://wp-answers.com/
I was wondering if it was fully compatible with BuddyPress?
@henrypwmoulton Doesn’t look to be compatible with BP and it looks more like a forum custom post type. Reminds me of a premium theme http://wordpressqa.com/
Having said that, the best way to find out if that plugin is compatible with BP would be to ask the plugin devs at http://wp-answers.com/contact
@imjscn I think the beauty is that there is no wrong way of going about it. Since I use MU, I don’t need CPT since the entire subsite is dedicated to the q/a. This keeps search separate from of different content types also keeps wp-admin only dedicated to q/a. I can only imagine when you do CPTs that managing the CPTs under one wp-admin it could get little overwhelming keeping those apart from other content but I’m not familiar with CPTs so I don’t know. I’ve only ever used a new blog when I need a new type of content. How does search work for cpt?
@nahummadrid , I agree, using multisite for different types or contents is better. But for now, I would stick to single site for this reason: https://buddypress.org/community/groups/installing-buddypress/forum/topic/buddypress-and-shared-hosting/
about the search, I totally discard BP or WP search, I use Google Custom Search instead. In Google search, you can add any section of your site, very flexible. For examoel, if you add http://mydomain.com/ , it will search entire domain, if you add http://mydomain .com/xyz , it will search this xyz
