I am not interested in charging my web site visitors a fee for any of the content that I am offering. I was simply giving an idea of what might be done with the ability.
I personally would like to allot new members a given amount of points that they can use towards posting questions (Creating new threads, what ever you want to call it). When they post the question, they figure out how much getting an answer is worth to them, in points, and they assign that amount of points to the question. When some one answers the question to the persons liking, the points are awarded to them and removed from the person who asked the question. This is a form of virtual payment.
Members who are rich in points are seen as knowledgeable, and as being active in the community. They are looked up to. Members compete to answer questions so they acquire more points. All of this is in an attempt to encourage community participation and to grow the site. If you have a web site where there are allot of people posting questions and those questions are actually being answered, people will come back more often and more and more new members will join.
So back to the example. Member1 posts a question and member2 ends up answering it. Member2 receives the points that member1 assigned to the questions and the points are debited from member1's account. Well now member1 has less points then they started with and they want to make sure that they can ask additional questions in the future, so they go looking through the forum at the various posts and start replying to threads that they know things about, in an attempt to answers some one else's question. Why? Because they are giving back to the community that helped them, and they want to make sure that they are apart of that community come the next time they need help. When some one excepts member1's answer, member1 receives the points assigned to the question they answered. Now member1 has additional points that they can use towards posting questions or accessing what ever other services the web site offers.
Chances are, since they were helped, they will help some one else. And most likely not just one more person but several.
You are certainly free to disagree with my idea but I have seen this work and work well.
http://www.experts-exchange.com/ is a hugely successful forum with a huge community of active users. They use this exact idea. If you take a quick look at there web site, one of the first things that you see, at the top of the page is "Hall of Fame", "Check out our IT Rock Stars. Proven Experts in over 100 technology channels". One of the first things that new people to the web site see are that this web site has allot of experts going through the forums. They know that there is going to be a good chance that some one will answer there question. I am a regular to EE and the technique works for me.
It's an additional feature that you can offer your users to encourage them to use your forum instead of some other web sites forum. That is what we want right? It's what I want. I want every user that comes to my web site to stay there, and when they do leave, to leave with the feeling that they can come back and post additional questions and expect a good percentage of there questions to be answered.
I'm sorry for the rant. I really feel that this would greatly improve this forums offerings and encourage additional customers. I know that I would have purchased this forum a week ago had this feature been present or in the works.