I've built two apps (MDB Viewer and Postico) because the tool I needed for my work didn't exist. It turns out, other people often have similar problems!
I was curious about your tools since it's really uncommon nowadays for one-man ventures to build desktop software. I'm assuming your Postico projecto is the postegres viewer. Not looking for exact numbers, but how is it selling? Are you able to make a living out of it, or it's mostly beer money?
My current revenue is around 10.000€ per month (mostly from Postico).
I'm not really a one-man venture anymore; I've recently hired a part time employee (I'd like to hire someone full time, but it's harder than I expected to find people)
There are lots of other one-man ventures making desktop apps. From the top of my head I can think of MarsEdit, Base from Menial, SQLPro manager, Acorn (image editor), Dash (documentation browser).... all Mac apps made by a single developer.