The first thing you need to do as you prepare to build your content funnel is to take an inventory of the channels that you're currently using, and chose the channels that you'd like to use in the near future. For example, when I set up a funnel for the Village of Shepherd's Maple Syrup Festival, I relied heavily on social media tools such as Twitter and Facebook, plus blogging tools such as Posterous, Blogger, and Wordpress. These were my channels.
These primary channels were supported by other online tools or services like Flickr and YouTube. While they played a smaller part, they were just as important as the services I listed above.
You should include in your list any email marketing services you are currently using, plus any discussion boards you frequent. These are all channels with their own unique audiences.