These are some of my favorites and none of them have more than 100 GR subscribers. Get with it, secmathedublogosphere! School doesn't start until Monday, right? Clear the dead weight out of your readers and add some new voices. (fair warning, this is slanted heavily toward high school math.) If you're thinking "I/my buddy should be on this list!" please add it in a comment.
Blogarithm - Insightful and honest.
Concrete Classroom - Don your safety goggles and dig in.
Math Recreation is not for drowsy bedtime reading but holy crap I love this blog. Get yourself a cup of coffee and enjoy.
Mathspig - Has an endearing habit of posting a hungry pig grunting post in between real (knock your geeky socks off) posts.
Mrs. H writes a blog with a beating heart. If you're an all-business blog reader, you might not get her.
Megan Golding - I forgive her for stealing my hairdo because she has the best profile pic.
Meta Musings - Is asking important questions.
Mr. K doesn't post that much, but when he drops something it's always worth reading.
Stop Trying to Inspire Me - Because sometimes your inner curmudgeon needs nurturing.
Transformed Educator - Living in the intersection where I spend most of my time - tech and how we use it to improve instruction, not just make it noisier.