Looking (modestly) for Google entries for my name the other day, I found an entry for JavaRanch; and found it displayed my email address!!! THIS probably explains why I've been getting some obviously dodgy (subject line in a strange mix of gibberish and Chinese characters) emails lately offering free Java code downloads.........good job I've got an effective spam filter.
I'm not sure that there is anything we can do about web spiders finding those addresses. If you don't want your address to be known to spammers, it's probably best to not make it public, as suggested above. You could still allow being contacted via private messages.
The soul is dyed the color of its thoughts. Think only on those things that are in line with your principles and can bear the light of day. The content of your character is your choice. Day by day, what you do is who you become. Your integrity is your destiny - it is the light that guides your way. - Heraclitus