Don writes Crossed Sabers, a cavalry blog. It has a hefty (and healthy) research journal flavor and dates back to February of this year.
Jim Schmidt in his Civil War Medicine recycles a little material now and again from his "Medical Department" column from The Civil War News. He writes long posts on interesting subjects like "Medical aspects of slavery." This offering seems to have been launched last month.
Scott Mingus in his Charge! Civil War wargaming & news does surprisingly little wargaming writeups per se. He is a miniature collector but his posts tend toward the more general type of Civil War travel and reflections fare. This project started in march and is somehow tied in with his newsletter, also called Charge!
(I noticed these three on JD's blogroll)
John David Hoptak, an Antietam NP Ranger, in January began The 48th Pennsylvania Veteran Volunteer Infantry, which is broader than it sounds. When he is "narrowcasting," JDH concerns himself with personalities of the regiment, historical problems, research, and a lot of "hands on" topics. When he is "broadcasting," the blog touches on regional Maryland and PA ACW material.
(I noticed this link at Harry's place.)
The USS Monitor Center has maintained a blog since May 2006; it keeps to something like a biweekly posting schedule and includes pictures galore. The fare includes snippets of news leavened with outbursts of enthusiasm.
Grapevine Dispatches is very visual with good taste in layout and image selection. Its anonymous author - I should call an editor - writes nothing, instead presenting all sorts of snippets from here and there. It's a potpourri that draws from poetry, contemporary articles, Wikipedia and more.
Steve Soper began the Third Michigan Infantry Research Project last November and is weighting his posts towards regimental soldier biographies and cemeteries. There are contemporary letters, too.
(These links were culled from Mike Koepke's list.)
Finally, I should look after my own business as well by reminding readers that my old (circa 1997) website Civil War Book News has this month been recast as a blog.
As a postscript, note also that there is a goodly number of ACW postings appearing on Chris Smith's Yankee Tirade.