Most people avoid forums like the plague when marketing, but there are those who plunge in headfirst, posting blatant ads everywhere. Neither of these two groups reaps many benefits from the very useful arena of forums.
You see, if you use them right, forums can be your best marketing ticket. You just need to make sure that you are presenting information, not a hard sell. People usually head to forums to find support and advice, so if you provide that, you can also mention your business when appropriate, or include it in your sig line.
The trick is to be a contributing member of the community. If you think of it in real world terms, a door-to-door salesman is like those who spam the forums, only there to sell. On the other hand, if you get a recommendation from a friend who has given good advice in the past, you`ll be far more likely to buy.
Being that good, helpful friend in forums will help you make the connections necessary to market.