It can also get you banned for spamming if you're not making a positive contribution to the forums.
Members who come to the board with the intention of getting their URL well known are most likely going to have their URL removed from the board and give themselves a bad name.
If you're going to go the route of joining a forum community, you should do it with the intention of making a good contribution and getting your business a foot-in-the-door, and anything after that is just a bonus.