Below is my list of everything I try and do to promote a new website.  I will at least seriously consider ever one of these below items, you should too:

• setup thoughtful content including meta keyword, meta description, title & alt tags for images
• identify similar sites & send out link reciprocity requests
• join a network like 9 rules (research industry specific sites)
• setup a blog
• setup a RSS feed
• setup an email newsletter
• add tell a friend links on key pages (product pages)
• submit site to search engines and directories see my list of sites I submit to
• submit site to design galleries & industry sites
• join industry forums & post with an email signature (keep on topic & not spammy)
• setup your email with a signature with your site URL & tagline
• make up bumper sticker’s for your cars with the site URL
• give out samples to prominent sites/blogs in exchange for reviews or at least links
• setup contests/giveaways on your site or other’s sites (maybe tie it to newsletter signups for entry)
• go old school and have business cards printed (authors should print bookmarks instead) 
• tell people you meet in person about the site and handout business cards
• network at industry events & handout business cards 
• add your URL to your social networking profiles (linkedin, facebook, myspace, facespace )
• create a widget that people can put on their sites to promote yours
• setup a google XML sitemap
• use paid advertising like google adwords & text links