1) When creating the signup registration forms for your webinar (available through Live Meeting Professional Edition), be sure to make the following fields a requirement: First and last name, job title, company, e-mail, company size, and vertical. These are all important statistics for knowing who your core audience is and will help you to make any necessary adjustments to ensure that the audience is presented to in a way that provides meaning for their particular needs.
2) Use as many free social media locations to promote your event, especially Linkedin, StumbleUpon, Facebook, and Twitter (for technology-related webinars, Reddit might be a good outlet as well). Be sure to include a link to the event registration page.
3) If possible, have a well-known blogger, author, or other company representative (such as a guru from Microsoft or YouTube channel) and promote them as a co-presenter (of course, they need to be presenting as well on the same topic). The perk to this promotional aspect is that you can gain their following as your audience as well (and vice-versa).
4) Run a search on Linkedin for groups interested in your topic. Join the group and create a topic thread related to your event on Linkedin (do not spam other topic threads unless you want to annoy group members, but once or twice is alright if the contribution makes sense).
5) Run a Bing search for websites that promote webinars and seminars and send your event information to the site. A popular resource is Webinar Directory.
6) Promote FREE material and information that will be downloadable at the end of the webinar for attendees, with offerings such as whitepapers, documentation, useful tips, etc.
7) Make it easy for other users to share your webinar event page information with others by including a Share This button or Tweet This button.
8) Blog about the webinar on a company blog or other blog site that you own/control and allow users to comment and ask questions about the event.
9) Interact with other blogs talking about your topic (Google blog search is helpful) by commenting on related posts. Be sure to include a link to your event page!
10) Keep a recorded copy of your webinar to edit and post to social networking sites such as YouTube and AuthorStream and be sure to promote your future events and website from the information section (and within the edited presentation).
11) During the webinar presentation, be sure to include a poll asking how many of your audience members are already familiar with the topic being discussed, whether they are already customers, or whether they plan to be. This can be helpful to generate future customers that are ready to buy and genuinely interested in your product or service.