Okay, so I haven't found many of them, but I wanted to share the ones I know about with y'all. If you know of any others, please feel free to post the links here.
gorionsward.tumblr.com - General Baldur's Gate blog. Posts a little bit of everything, but mostly screenshots, news, and concept art.
askodesseiron.tumblr.com - In-character ask blog for Edwin. I am pretty sure it's no longer active, but the answers that are there are amusing to read.
ask-xanofevereska.tumblr.com - In-character ask blog for Xan. Still active. I know because I'm the one who runs it. Feel free to ask questions.
There was one more I remember that was documenting a rather hilarious BG1 playthrough, but I can't for the life of me find it or remember the URL.
gorionsward.tumblr.com - General Baldur's Gate blog. Posts a little bit of everything, but mostly screenshots, news, and concept art.
askodesseiron.tumblr.com - In-character ask blog for Edwin. I am pretty sure it's no longer active, but the answers that are there are amusing to read.
ask-xanofevereska.tumblr.com - In-character ask blog for Xan. Still active. I know because I'm the one who runs it. Feel free to ask questions.
There was one more I remember that was documenting a rather hilarious BG1 playthrough, but I can't for the life of me find it or remember the URL.