one way to make it a little more difficult to be found on search engines, make sure your forum profile uses 2 separate names (one to logon with and the other is displayed in the forum).

for instance, Google search engine picks up Psych Central members' logon names only. i have a different logon name, and when i search the phrase "jennie AND 'psych central'" nothing appears. however, when i search my secret logon name and "psych central" there are a few of my posts linked.