send a bunch of coasters with your website on it to the bars so when people are drowning in their sorrows wishing they had a soulmate they will join your site
Radio ads, flyers on college campuses, flyers at any area with your demographic you need, piss the name of the website in the snow, jerk off on people's faces while screaming the name in public
we have had positive ROI with some very targeted print ads for dating. It has not been a huge return but we have left it in place b/c it has stayed positive month after month.