The article about productivity improvement was intended as an unremarkable first post, just to have something in our blog before "more serious" content. But it got a ton of upvotes on Reddit and Hacker News, bringing at least $4,000 in additional revenue that month.
So far it's the most successful article with over 125,000 unique readers in a year. It also beats all other posts in conversions to sales because Qbserve is directly recommended in the text.