Video is responsible for over half of all traffic to websites, so it's no surprise that webinars can not only drive traffic but help you build a highly responsive email list.
Also see Grow Your List with Webinars, which takes you through the process of using webinars to generate leads and sales.
If you want to build your list with webinars, your webinar software should easily integrate with other technology such as your email autoresponder and social media for marketing.