I think that the most interesting blogs usually share something that is unique to the person writing it and they always include photos (visuals are key!). For example, if the blogger is a foodie - instead of just saying "this is a recipe I like" and posting some recipe, they go ahead and make it, post photos of them making it, and then add their own tips to it. Likewise I find that the mom blogs I keep coming back to are those that simply blog about their daily life, their experiences, and supplement it all with great photos.