Maybe word of mouth is an effect, but I doubt it's a significant one.
If I recall correctly- most of his traffic comes in through long tail keyword searches, which he constructs mini-sites for (e.g. Halloween Bingo Card maker). In these cases I expect that keyword matches, and relevant content are a lot more relevant than links from tech sites (which mostly go to his blog, on a separate domain)
That's the way I remember it, he was already somewhat successful because of his taking advantage of an under-served niche market. Most of what I remember is him talking about how he expanded it and chased the long tail. I'm sure he's had a boost since he started talking about it though.
I suddenly feel the need to read through his posts again.
If I recall correctly- most of his traffic comes in through long tail keyword searches, which he constructs mini-sites for (e.g. Halloween Bingo Card maker). In these cases I expect that keyword matches, and relevant content are a lot more relevant than links from tech sites (which mostly go to his blog, on a separate domain)