Sometimes, a blog becomes popular enough that it turns into a book – a phenomenon knows as a "blook." One example is Julia & Julia, a book that grew out of one women's determination to cook her way through Julia Child's Mastering the Art of French Cooking. [Full disclosure: I started and stopped the book on the same day.] Last December, the New York Times looked at a couple of blooks, one a collection of secrets, the other a woman's call to refrain from premarital sex.
Here's an older USA Today story on the same topic.
I will say I liked Wendy McClure's I'm Not the New Me, mostly because I fell in love with her comments online about some 1974 Weight Watchers cards. (Check it out for yourself here). But since I primarily read fiction, I probably will never read a lot of blooks.
In novels, there are several YA titles that feature a blogger.