The easiest
Moving on to more serious/functional stuff, I eventually decided to sign up for DISQUS. I went back and forth on this because I couldn't figure out from what I was seeing how it improved anything. I suppose I signed up for it mostly to see how it worked. Although now I'm confused: since I had to shut Blogger's comments down to get DISQUS to work, do readers have to be signed into DISQUS to make any comments at all? Gah.
Site statistics intrigue me. I'm delaying signing up for any, however, since most of them looked like overkill. But I would certainly try to set them up on a library blog: we all know libraries live and die by their statistics! So far, this hasn't seemed like a blog that would benefit from adding audio or video gadgets. If I were writing a more personal blog, though, I'd probably want to add photos and the occasional video. As for a professional blog, I'm certain we could find a use for those widgets. With this particular blog, though, it really would be bling: flashy, eye-catching, but not much in the way of functional.
The time consumption is pretty high for this Thing. Installation and sign-up usually didn't take long, but working through lists of widgets, reading about them, sorting them out in my head, testing them, and so on took quite a while. I eventually made myself stop just so I could get this posted before February. Although if we do set up a library blog at some point in the future, at least my preliminary research is taken care of.