Hi Jason, Such a great idea to ask the community for help and ideas. Here are a few of mine:
Badges/Buttons-The badges here are used internally to this site (which is fine) but you could implement a public badge creator that enables people to embed an OnStartups Answers badge/button on their blog or website that links to this site. This would be similar to the many Twitter button creators, etc.
Email Newsletter- Although many people use RSS feeds, some people prefer to subscribe to forums via email and receive a weekly or monthly round-up of top questions and answers. This is a great way for people to opt-in to receive information (even if they don't register with the Answers site), and emails are often forwarded to others. To increase email subscriptions, or just offer on its own without registration form if you want to take a more viral approach, offer a relevant, useful eBook, video, or other type of content that they immediately receive. This content should be optimized to be shared via social media, furthering its reach.
Video Campaign- Create a series (start with one video, test it, analyze results, create second video, and so on) of short videos and post to YouTube and the OnStartups blog. Include a strong call-to-action, for example the "Google inbound marketing" CTA that HubSpot used in You Oughta Know Inbound Marketing" video.
SEO Press Release-Simple, short press release announcing two successful software entrepreneurs started free community to help other startups. Do some keyword research and be sure to include keywords in release and provide link to Answers site. PRLog is my preferred free or low-cost release distribution site.
Contest- The person that submits a question that gets the most community votes during a specific month, and the person that has the top answer during that specific month, each receive a free 1 hour conference call with you and Dharmesh to receive valuable advice on their most challenging problems. Since only active community users with high enough internal badges can vote, this would prevent cheating.