Recently, quite a few blank blogs have been being posted around the wiki. Sometimes users fill them in with content, other times they don't. I've had to delete a couple, and I've seen other admins have to do so too. Apparently it's a bug with Wikia, but there is a way to stop it. When you're creating a blog page, and the dialogue box appears asking you to type in a name for your blog, use the OK button to submit that title. If you press the enter key, the blog will be submitted without any content. Normally this would be prevented, since pages can't be empty, but the "Blog posts" category technically counts as content, so the creation goes through.
TL;DR: Use the OK button to submit the name of your blog, not the enter key.
UPDATE: We now have a spam filter running which prevents blank blogs from being posted. It's been in use for over a month now, and in that time, we haven't had a single blank blog posted (that I've seen). So, basically, don't worry about this anymore, if you use the enter button it should still be alright.