One thing you could do is ask for marketing help at various forums. For e.g. you could post it here as another Ask HN - "Ask HN: Help me market xyz.com". Apart from getting plenty of good marketing ideas, you might find your business co-founder.

Other forums I would look at are the ones focused on SEO like inbound.org, growthhackers, trafficplanet, BHW, WF etc

Also, put your email ID and the link to your tool in your HN profile. I'm sure there are plenty of people in SEO here who will be happy to help.