1) Unique keywords: By tracking the number of unique keywords your site is found for, you’ll see a global, birds eye view of how well your site is doing with the long tails. Sure, you want to be found for the important, high volume terms as well, but a healthy site will rank organically for a great diversity of keywords.

2) Organic Visits Per Page: Every page on your site should target a few keywords and draw in traffic for those terms. In other words, what percent of your total unique pages are doing a good job of bringing traffic? If you have 1000 pages, and only 200 unique keyword visits, you’ve got some issues that need to be addressed.

3) Conversion Rate Per Keyword: It’s extremely important to know which keywords outperform others. As a search marketer, your time is very limited. Therefore, you must focus on the terms which return decent ROI.


Here's more info: http://www.palmerwebmarketing.com/blog/alternatives-to-google-pagerank-7-worthwhile-seo-metrics/