Q & A type of sites generally get a lot of traffic which can be channelized to your main websites and increase your revenue. Q & A is a proven business model for many years with successful sites like Stack Overflow, eHow etc.
If you are looking forward to create a how to site, there is s new Q & A Plugin called AnsPress which looks promising. AnsPress a most advance community question and answer system for WordPress plugin which is still under development, however you can use it & keep an eye on the updates.
Some of the features which will available in version 1.0 are:
- User point system
- Better voting system
- Better admin interface
- User profile
- Choose Best Answer for Question
- Revision control
- Multiple authors
- Point based user access
- Filter questions
- Sort answers by votes and date
- Quick ajax search system
- Ajax based form submit