These bloggers make anywhere between $15 and $75 per CC approval. You do the math. As a small site, there is little money to be made, but a large one can certainly pull in a decent chunk of change.
If you have a decent site with good traffic (>25K uniques/month), you can probably also find some flat rate banner sponsors for $150-$200/month. Pop in the usual crap like Amazon affiliate links and you have yourself a business.
Bottom line - there is definitely some money to be made.