The first rule of search engine marketing? Don’t talk about Fight Club. The second? Never let an opportunity pass you by. Every line of code, every social profile — it’s all a chance to promote yourself online.

Take the Ajax Union 404 page. Of course, all of our links are flawless, but you can get there by attempting to travel to something silly, like www.ajaxunion.com/great-white-sharks-are-awesome.

Some 404 pages just say “We couldn’t find the page you were looking for,” or similar, but not ours. Our 404 page includes:

• A video
• Links to our blog, Facebook, Twitter, LinkedIn, Youtube, and Tumblr
• Our phone number
• Unparalleled wit

Pretty neat, huh? Next time you’re designing a website, just remember: any place for text is a place for online marketing. (Also: Don’t talk about Fight Club.)

If you work for a search engine agency, you probably hate nofollow tags.

These loathsome elements reside within HTML link tags, signifying, in plain language: “Hey Google, please do not take this link into account when ranking pages.” There goes your backlink.

(Nofollow tags can be very valuable to webmasters looking to streamline their internal linking for a better site representation on Google. But for off page SEO, they’re pretty much bad news.)

Nofollow tags are commonly used by services vulnerable to SEO spam, particularly social networking sites like Twitter, Facebook, LinkedIn, and MySpace. But, as many search engine marketing experts have speculated, Google might actually be following some nofollows — namely, the nofollows associated with important social networks. Like Twitter.

SEOmoz recently explored the potential value of Twitter’s nofollow links. The experiment ended with an optimistic conclusion — that listing the URLs of new pages on Twitter tends to get them indexed quickly.

What could this mean for search engine marketing? That nofollow links might not be such a waste of time. Go forth and tweet!