Gosh, I'm not going to be able to narrow it down to just one blog. There are so many blogs for which I am thankful, so I'm going to list my top 5 (in no particular order):
Myrtle's was the first blog I ever read ... even before it was a blog. I still have printouts of her email newsletters from the 1990s! Her blog led me to her "Beginning Blogging" webinar, and the rest is history. Now, a little over one year and 160+ posts later, I'd say that at least some of what she taught me has stuck. I'd recommend this blog to anyone even considering diving into genealogy OR blogging (or both!).
It's All Relative
I am extremely thankful for my dear friend Laura Aanenson's blog. Without her blog, we never would have made the connection to become our Success Team. And what a success it has been! Even through our "technical" failures, we continue to learn from each other, and to push each other to do more than we think we are able. I highly recommend a "Success Team" buddy for everyone (especially if you can't afford a therapist).
Genealogy Tip of the Day and Search Tip of the Day
Michael John Neill pops out these little seeds of genealogical wisdom on a (more or less) daily basis, and no matter how experienced you think you are ... there is something in there that you can use, or that will remind of something you forgot. Plus, there's also the Casefile Clues and Casefile Clues for Beginners (both subscriptions) that are great ways to pick up new places to look for clues and new ways to look at the data you already have.
Documenting the Details
Linda McCauley has been blogging for two years and researching her family history for over a decade, and knows her stuff. The reason I'm thankful for her blog is because she doesn't only tell her readers about her successes. She also isn't afraid to let us know if she goofed and why - and more importantly, how she intends to fix it. It is through her blog that many genealogists and bloggers alike, no matter their experience level, can pick up some little nugget of knowledge and be all the better for it.