Daring Fireball   Money Machine?Editor’s note: On occasion we will be taking back-of-the-envelope revenue looks at companies, blogs, and startups. Today, we look at a very interesting blog.

Everyone in the technology world knows John Gruber, the dynamic Apple blogger who writes Daring Fireball. Daring Fireball is a must read for technology insiders in any circle. He nearly always has a voice of authority in every Apple situation.

But Gruber has done something else beside form cultivating numerous friends inside of Apple, he mas made Daring Fireball into a serious business. Let’s take a look under the hood.

To begin with, Gruber sells weekly sponsorships at $3,000 a week. Just one at a time, but for one man’s blog, that is a tidy sum. As we speak, sponsorships are sold out for the next 14 weeks. The next open spot is in May.

At 3,000 dollars a week, that puts Gruber at $150,000 year from the start. Not a bad start.

But Gruber also sells memberships to Daring Fireball, at $19 a year. Who would buy a blog membership, you ask? Well, think about how dedicated Apple fans are. That spills over to Apple blog readers. Now Gruber claims to have some 150,000 subscribers and 1.75 million monthly page views. We will work from that.

With 150,000 dedicated readers via RSS, and hundreds of thousands more via the website, how many are subscribing? Let’s just say 1% of his dedicated readers. So, that would be 1,500 from the RSS numbers, and say 3,000 from a (guess) of 300,000 unique visitors a month.

That would mean a total of 4,500 subscriptions at $19 a piece. That would be another $85,500 in revenue yearly. Add the two together and what do you get? Some $235,500 dollars. Nearly a quarter million dollars a year, from just one man blogging.

Quite impressive, Mr Gruber.