The majority of the side projects I work on just because it's fun to work on something; if people actually use it then great, but if not, the project will just wait until someone eventually comes in. With this approach, it's not “marketing”, it's just working on a hobby project, which, besides the coding, may include marketing activities, SEO and whatnot.
Thanks, that's a good perspective. I like the idea of treating marketing as just another part of working on the project, rather than a separate task.