Let me first say that I have never marketed anything before I made my app.
Since I don't want to spend on ads and my SEO is miserable right now I thought: Lets make something that is free and useful!
Enter the Book Writing Calculator
This is a simple tool on my homepage to help people figure out how long it would take them to finish writing their book or novel.
Got a massive spike in traffic after I posted this in r/writing.
Some people seem to use this calculator to check regularly on their progress so I see repeat users come to this page.
No conversions. Not many people stuck around.
What I learned
I only had a small link to the homepage on the bottom of the page. I should have been more aggressive. Also this was before I had a free version of my app. People who come for free tools want free tools first, I guess.