It's the rest of it. I've always worked on sites with an assload of traffic, so its all about optimising their experience. When you are starting something from nothing the hard bit is actually getting some damn traffic in the first place. It takes so very long to build any momentum that its really easy to get disheartened. It's like watching compound interest on a bank account, nothing interesting happens until the last few years. You could actually be getting a decent rate of growth but if thats 10% on five users its still gonna take a while.
At the moment I'm working on two sites notusingit.com which is essentially a listings site, they are only useful to people if they have listings on them so you are well into Metcalfe's Law territory which makes it very hard to build and audience. I've had to go down the (very slow) SEO route trying to gradually build more traffic and more listing. Its a free site at the moment so buying traffic would be silly.
At the opposite end of the spectrum is customerreminder.co.uk there is no network effect in action here and the customers are actually going to have to pay for stuff. So this is very much a target for adwords. But again the problem is its hard to optimise adwords until you have lost a bit of money in the process.
But you know fun and games, and importantly learning new stuff. But none of it is about the code.