I'm curious to hear what ideas people have about promoting a webcomic. I think this could be beneficial to everyone to share ideas here. I have a few to share, that I think help, but who knows, there might be better ideas out there.
First, and I picked this up online from one of the freelancer sites I visit. Companies pay for bloggers to go out and leave comments on sites with valid comments, in order to save a BACKLINK to the site they want to have advertised. This should NOT be confused with spambots leaving generic comments on blogs around the world but rather, the people who do these jobs are to find blogs on a certain topic (e.g. apartments, google keywords, etc) and then leave a valid, related comment on the blogs they visit with their name, email and URL. That URL is the backlink to a site that businesses pay to have advertised. This promotes the site in two ways: first, any reader of the comment can check out the link and go to the site and second, search engines will pick up this link and add it to their listing (at least, I think this is how it's supposed to work. I'm still reading about how search engine optimization(SEO) works.)
So in other words, an important way to advertise your site is to visit blogs and leave comments with your URL. These backlinks help build up traffic. Additionally helpful are sites with "commentLuv" turned on. This plugin will not only allow you to leave a comment and your url, but it will leave a blurb about what your own last blog posting was about (CommentLuv is pretty easy to work with. If you have Wordpress, it's just a plugin to install and activate.)
Another promotion idea is Entrecard. I'm still getting the hang of this, but basically it's a FREE ad you add to your site, and it shares links with other Entercard users. It's a way to get your ads on other sites for free, and it's also a way to network with other bloggers. Again, I haven't totally figured it out, but I like the fact that any ads that appear on your site you need to approve first, before they can appear.
Anyhow, those are just a couple suggestions. Let me know if you have any others that you can think of. Thanks!