I prefer not to look at ad revenue in eCPM terms. I look at revenue per visit, CPC and conversion rate (clicks per visitor).
Yep. I have been monitoring these metrics for years.
Except for a slight increase in EPC, all other metrics have dropped significantly, when comparing year on year. Having said that, I should add that 'revenue per visit' appeared as the most solid metric until the financial meltdown set in.