Another metric I find quite interesting is "impressions by placements". This is a measure of how people came to see my adverts (in a list of other adverts).
Broken down by placement:
Top 20 search slot impressions: 20.0%
Rest of search slot impressions: 26.6%
Non-search impression: 53.4%
"Non-search impressions" are where people saw my advert listed anywhere outside of explicit search results, such as in 'Similar Items' or 'People who viewed this item also viewed'.
As a buyer on eBay, I also suspect that most of my buys come through the non-search impression route.