What are the top 5 KPIs to measure on an eCommerce website?

- Number of visitors
- Conversion rate
- Profit per unique visitor
- Cost per unique visitor
- % returing customers

Jason, if Alex's metric of "conversion rate" also defines those shoppers who abandon their shopping cart, that may point you to lost sales/margin and thus to ideas to improve conversion.
Regards
Len

Why 5, here are the top 3 must haves:

1. conversion rate for each page through the checkout series till payment
2. % of returning visitors (association with revenue) and duration
3. Revenue by lead source (SEO, marketing campaign, etc)

If you must measure 5, there are two more:

1. Lead capture conversion rate from home or key PPC landing page
2. Bounce rates of key pages

Revenue by lead source is a KPI for us for marketing, not for the website itself. We break down indicators for both. We also track the devices to see if mobil shoppers are spending or browsing compared to PC shoppers.