This is not really proper post, it is a collection of points I have repeated to many people (last posted in a Hacker News thread). Figured it would be a good idea to have it put up somewhere.
What it is a list of metrics you need to track when you run an online operation and the importance of each element:
1. Page views: Track overall growth
2. Page views per user: Track engagement
3. Visits: Track overall growth.
4. Unique visitors: largely useless metric since every tool out there disagrees with each other on the number.
5. Revenue per user: Track user segmentation.
6. Revenue per page view: Track infrastructure costs.
7. Active users: Finer measure of engagement and churn.
8. User acquisition/retention cost: Track cost of marketing/outreach.
9. Conversions: Free to registered, registered to paid.
10. Off-site: Notification emails, Newsletter subscribers, open rates, Twitter followers, Facebook fans.
(1) Important for selling inventory on CPM.
(2) Needed to get the mix of organic growth with existing users to increase, while keeping a different focus on acquiring new users.
(3) Needed for the ad sales pitch. No point getting a million visitors if you can't retain them, but sales needs inventory.
(4) This has always been ~10% off between different tools. Can be an indicative measure of engagement.
(5) Helps keep ceilings in place for acceptable cost per user.
(6) Helps make decisions on infrastructure where you need more than what you can buy.
(7) Possibly the only user-related metric that should matter internally.
(8) Can help you understand why bidding on that $5 CPC keyword does not make sense when what you make per user is $3.
(9) Helps you fine tune monetization.
(10) Helps you cover all other external delivery platforms.