I get tired of technical environments online which assume there are no women present; or worse, that outright insult them. Slashdot and digg are particular bad

I get tired of technical environments online which assume there are no women present; or worse, that outright insult them. Slashdot and digg are particular bad about this, but you see some of that here as well. What message is that going to send to people who are considering joining the field? Who would want to deal with these jerks? Assume that there are women present, even if you don't hear from them, and act civilly. That will make room for more women to come in. Thanks.