One thing I've found repeatedly is that commenting on other blogs is worth doing because as well as getting a link in the comment thread, it can result in backlinks being given by that blogger, or another blogger who reads the comment thread.
Here's a recent example: As I mentioned below, I've been building and promoting a satirical character blog. The character, Derek Sapphire, is basically a distillation of all the extreme left wing, politically correct and deep green dogma that we are constantly bombarded with and which so many people feel increasingly annoyed by.
I thought a good way of getting him known in the blogosphere was to have him write some comments on some of the more rebellious and provocative right-wing blogs. I knew there was a slight chance that some might be tricked into thinking that he was real (although that was definitely not the intention). But I assumed that most would see that he was a joke and play along with it. Although I wasn't doing this just for backlinks, I thought that maybe some would result from this, which would be a nice bonus.
And yes, that has happened, but it hasn't gone quite as expected! Firstly, posing as Derek, I wrote some comments on this post. The blogger seemed to see it was a joke, and played along with it. So did some of the readers, although I think there was a bit of confusion about whether he was real.
Anyway, one of them posted a guest post that linked back to one of Derek's posts. Playing along with the gag, he facetiously claimed that Derek had made a brilliant sage-like prediction.
I wrote several other comments as Derek, which was a lot of fun. But I think the readers there were starting to tire of him after a while, so I decided to give it a rest. (I will return again, though.)
That seemed to go reasonably well, so I tried it at a few other similar blogs. On one of them, they really thought he was real, and the character got a whole lot of abuse hurled at him in comments. Please note that this blog has some NSFW images before clicking. These are the relevant posts.
As you'll see, some of the readers suspected he was satire, but several didn't. Finally they all came round to the view that it was all a joke.
I almost felt bad about this. I didn't want to fool them. And it's understandable that some people thought he was real. He is actually based on many people I've met. People like him do actually exist, some even more ridiculous and extreme than he is! And even though it says the site is comedy and satire in the meta-description, you don't see that unless you come via search engines.
As well as the links in the comment threads mentioned above, I've just discovered a backlink from another American right-wing, climate skeptic blog. This blogger seems to think the character is genuine, so maybe he saw one of the other comments I'd written as Derek or perhaps read the above mentioned thread very early on? In any case I left a note (as me!) in his comments, because I don't like this idea that people think he's real. Derek Sapphire is a satire, not a hoax.
That said, it still goes to show that comments can result in backlinks. And just to repeat: I wasn't doing this only for backlinks. I wanted to have some fun, give people a laugh and of course promote the character blog. But as you can see it certainly has worked SEO-wise.
Of course the fact that he's such an annoying and colorful character made him stand out. So that's something to remember. It's worth taking some risks when you comment. That will increase the chances of this technique working.
One more thing: By linking to Derek's blog, all those blogs mentioned do also benefit SEO-wise. They're getting one way links from this blog.