Ok, so Twitter would work then by getting your Twitter followers?I think there should be a choice between both but honestly I would be okay with their not being a DM option because I did my research and learned from experts and experience that most people don't read their DMs and when they do get them most are pissed off that it's 'spam'. Tweets directly to someone's walls actually results back in more traffic to your site because their followers will see your tweet and investigate and just because they ignored it doesn't mean some of their followers will.
And probably post something like:
@8thos, check out this site blah <shortened URL>