Lee Odden suggests that customer interaction can be great blog material.

It’s a good idea. Lots of businesses have customer service groups and many of them capture customer conversations in their databases. Why not take the best questions and answers, clean them up and expose them on a blog? So what if it’s the same as an FAQ? This approach is faster and it’ll probably do better on search results.

Add this to your list of successful approaches to blogging that don’t require a lot of time or money.