I have been testing an ad using [tag]Feedburner[/tag], and their new rss ad feature. I did the test during May and I paid $10 for 2,000 impressions. The ad was for [tag]Amigo Health[/tag] and it was only showing at blogs writing about [tag]health[/tag] and wellness.
The results was 1,991 impressions (not 2,000), 65 clicks and a CTR of 3,265%. None of the 65 clicks resulted in any sales, but I think it was an ok result. The ad I wrote could probably be a little better and the landing page could have been better and so on. And 65 clicks from $10 isn´t that bad.
I will probably do another test during June.