Participating in Yahoo! Answers not only contributes to the community and helps people, it is also a potential source of traffic to your forum and a potential source of new members.
Do a search for the keyword(s) related to your forum and look for questions that need to be answered. Answer them. Add a link to your forum in the box for the source of the information (assuming that there is something relevant on your forum to the answer!).
Don’t you hate spammers, fluff posters and link droppers on your forum? So, do not be a spammer, fluff poster and link dropper at Yahoo! Answers – they hate them just as much there. Be a useful member of the community; impress people; they will click on the link to your forum (don’t be a SEO Kiddie). The links are nofollow’d so do not use them as a hope to build backlinks (some webmasters have reported seeing Yahoo! Answers link in the backlinks reported by Google and have wrongly assumed this to mean that Google do pass link juice from them. Google have confirmed that they can and do report nofollow’d links in the backlink sample, but they do not pass link juice from them).
To speed by the daily task of checking Yahoo! Answers, do your keyword search and make the search results page one of your Firefox home pages (I have several Yahoo! Answers keyword results pages set as some of the many home pages in Firefox, and check them several times a day). For example, here is the url to set as a one home page in Firefox for ‘gout’: