One of the SEO theories I have heard is that if Google finds a plain text URL in your content, it might interpret that URL as some kind of signal.
It was so awkward that even Matt Cutts, the Google Search Engineer, made a video about that.
Why bother about plain text URL?
Why bothering about plain text URL if even Matt Cutts said they are not counted as a signal nor as a valid inbound link?
That's my small experience, which maybe is not interesting at all, but possibly it would open the door to some extra thinking.
Taking care about the net, the brands, the social media sphere and UGC to understand what happens outside require necessarily to monitor every single channel in plenty of ways.
One of the methods I prefer is using the Google Alert service that periodically sent me an email (or more than one according to how many SERP you are going to check) within all the links the search engine found on the net during the given timeframe.
That's the point. In more than one occasion I got some alert containing a reference specifically setup to track only links where the destination page reported to me wasn't containing a link at all, but just a mention of the link in a plain text.
For instance, instead of getting back a page with I got just a plain reference such as http://www.andreamoro.eu/
At this point a couple of questions raised into my mind. Do plain links count as a link to the URL? Does this contribute to the URL's authority?
Again, I reckon this won't do, but the fact is that you can never be too confident about these sorts of declarations. Sometimes these theories end up being partially true, simply because Google engineers have overlooked rare cases that indirectly validate the theory.