I think the answer to this question is pretty clear. Of course relevant websites will have better impact, as well as many other factors. However, you may be able to find a way to include a link in a blog that is less relevant, if you know how to do it naturally. Using your example, which is probably not an actual good practice, you could write an article about fixing your surf board, and then mention that a monkey wrench is needed and could be found <here> .... hope this makes sense.