The Wall Street Journal published an artilce called  Blogging for Money with a discussion between Jason Calacanis and Alan Meckler; it makes an interesting read; especially the part about how some blogs are making money.

Jason Calacanis writes:  "Today you can start a blog, build an audience, and give the advertising slots to AdBrite or Google AdSense. With three or four ad slots you’re gonna do a $3 to $10 RPM (revenue per 1,000 pages viewed) with these automated tools on average. So, if you can do 500,000 pages a month — which isn’t easy – you can make $1,500 to $5,000 a month. That’s today and without a sales person. That number will go up over time and some folks might even be able to hire a dedicated sales person at some point. Solo blogging is starting to pay rates similar to the smaller media outlets (think local newspaper or a small magazine). Walt Mossberg might not be running out the door to start a blog, but it’s only a matter of time in my mind."

With 300,000 pages in the B2B [business to business] space you could RPM at $15-$50. That’s $4,500 to $15,000 a month, or around $50,000 to $180,000 a year. You make $242,000 a year according to Yahoo Finance — the candy bar gap is closing!

I think the numbers are probably better than what’s quoted above.