Dosh Dosh has a great post about 6 Fool-Proof Steps to Make More Money With Your Website. It's well worth taking your time to read it. Here are the 4 desired outcomes of taking these 6 steps:

1. Monetize. Get more (or some!) revenue out of each post.
2. Capture Leads. Encourage a visitor to subscribe to your mailing list.
3. Improve Relevance. Provide an improved user experience for all.
4. Make it Rank Better.  Doing on-site and off-site optimization will help specific money pages to rank better on the search engine result pages.

Each is a great reason for optimizing your most popular pages. Give it a read and try to implement the suggestions. They're worth doing.

I ran across a very good run-down on Search Engine Optimization over at SEM Labs. Rather than attempt to recreate the wheel, I'm just going to refer you to the article. It's well worth the 10 minute read.

By the way, this "find" leads me to another thought – I "found" this article through the Comments section of another blog I run (the Muscle-Build.com Blog) – the author of the comment is the man behind SEM Labs. You NEVER know what you're going to find in your Comments (so check them – they sometimes are GOLD)!