In recent months I started getting some Google traffic from the phrase "search engine optimisation tips" even though I hadn't targeted that at all. Presumably this was because the search engine is pretty smart and knows what the acronym stands for. But remember there are two ways to spell the word "optimisation" -- one with an "s" and one with a "z". And at that point I hadn't had any visitors arrive via searches for the latter version.
So I've done a bit of backlink building over recent weeks, alternating between the two versions in the anchor text. I'm now on page one for both of them, and getting a couple more hits a day on average. Sure, that's not much, but every little bit helps. And it will build as I keep chipping away.
So, there's definitely something to remember there. If you're targeting a keyword phrase, see if there's an acronym for it. And also look for different ways to spell it. Then build links using all those different versions. You could end up drawing in quite a bit of extra search engine traffic as a result.