Bounty programs offering members rewards can combine extremely well with public communities. You have a lot of people enthusiastic about you (and your topic). You can set a challenge and offer them a reward.
With a former client, we offered $10 to any member who identified an error in the community after a migration had caused some issues. The speed and scale of response was fantastic.
You can easily expand upon this to your main site too. You can set a bounty and challenge members to identify any errors on product pages, in the customer experience, or even tiny things like SEO optimisation (most communities include a few tech-heads).
A few tips for making this work.
1) You need a central system for members to ‘file’ the issues they see. Otherwise, several members might report the same issue. Whoever files the issue first gets the credit. It helps if members can see which issues have been identified already.
2) You need to review and approach each of these quickly and easily. Ensuring consistency of approving issues is the real challenge.
3) You need to cap the limit any member can earn in a month. This should never become a substitute for employment for any participant in the program.
4) You need to be clear about what counts as an ‘individual’ bug. For example, if a website isn’t set up correctly, the same problem might show up on thousands of pages. That’s one issue, not thousands of issues.
5) Trial this in one area first. Target one small area of your community or invite only a select group of people to participate. Make sure there’s no problem in paying members, you have a system that works, and overcome any early challenges before expanding to the entire community.