What exactly are you trying to accomplish? Are you trying to build the community and engage the existing users? I'm going to assume both is true. But the first thing you need to ask yourself is what are your goals with the community. Then ask yourself what tone do you want to set for it? Start by reviewing the communities of similar sites in your market. Some great examples would be the 37 Signals and Zappos communities. Balsamiq also has a great community too. All of them share a common trait: There is a personable approach in their writing and sharing.

A few things: Instead of asking for PR at blogs, offer to guest blog at those places. It opens your company to a broader audience. Make sure to follow up on every single comment too. Then offer other companies' community managers to guest blog on your site. They will make sure to tweet/FB their posts to their audiences and it starts a reciprocal relationship.

Email is underrated. Yeah, I know people think its dead but we send out an email each week and highlight product developments, share articles relevant to our users, and highlight our blog posts. We have a very high open/click-through rate and see an increase in Twitter chatter for about 3 days post-mail.

Next, highlight your users: show the community how people are using your site/product/widget and ask your community to guest blog for you. Highlight your users in your weekly emails and tweet out their stories/contributions.

Have webinars or twitter chats that scheduled and have a unique hashtag. They don't have to be directly related to your product but a general discussion about the industry. Reach out to businesses in your field and ask them to co-host these with you in a roundtable fashion or Q&A setting.

The above should get you started and spark more ideas along the way. And the best part is you can do all of these at no cost except the time you spend. Good luck!