Right now, I believe the related blogs module shows blogs related by tags, but if a blogger isn't good at using tags, it can be left empty. So this might help:
Define in the settings how a blog is determined to be related. Maybe a checkbox that allows me to select either related by tags, related by blog category, or related by author (i.e., show other posts from the same author.)
Second, I would suggest have the "sorting" option include a "random" option.