I tried Yahoo Answers, I got bored after some weeks and gave up. Have not seen any benefits from using it, there are other better methods than this.

I used Yahoo Answers to promote a website once and it worked great but it gets a little boring and difficult after awhile

I think too that there are better ways to promote something. YahooAnswers won't bring so much traffic, but it can be a fun and easy promoting method.
Users post questions, and other users do their best to answer those questions. In your answer, which has to be as relevant as possible, you include a link to the source. That's all.

Can you tell a bit more about it? I have never tried and I have no idea about it.

i also ever tried to use yahoo answer, but i don't see any benefit using it.. (someone reported me and i got banned)

Links from Yahoo! Answers are nofollow, which means that they don't pass PageRank. Having this on mind - from the SEO point of view, Yahoo! Answers are not worth their while because they don't help you in the search engine result pages.

However, I believe that Yahoo! Answers, if played right, can bring a lot of targeted traffic to your site, and that can help you promote your products, services etc.

That's why I think they're worth their while. You can build links elsewhere

Good luck!