Seth has a short but sweet post that makes an important but simple point; one of those that seems obvious...but only when it's pointed out to you.
And it is this. That online, finding what you want isn't the problem; knowing what you want to find is.
Because no matter how strange or obscure the thing you're looking for, it's out there somewhere…and probably in quite significant volume. In other words, it's just one quick Google search away.
But if you (or your consumers) don't know 'it' is what they are after, they can't start to search.
Which defines possibly the big challenge of the long tail digital space - helping people think imaginatively enough to seek out the unexpected.