My smallest python program was for filtering wifi names according to patterns. I hab collected some wifi names atomatically via sone other programs, and had them sitting in a text file with one name per line (a very simple data format). I wanted to find interesting names out of it, but didn’t want to spend much time scrolling through hundreds of names following the same pattern, like ISP-12C5, ISP-3F4B, … So i invented my own pattern syntax for very simple patterns, (ISP-%4Ax for ISP- followed by 4 hexadecimal digits with only capital letters), and wrote up a python script that read patterns from a file, and then filtered the standard input against those patters. any line not matching any pattern was then printed.

In short it was a small project that i wanted to do, with simple data formats that i could easily parse and relatively simpel logic that i had ideas how to implement while designing the patterns. And i had some data to test it on.

So my advice is similar to the other people here: look for things you are interested in or you need that sound simple to program, and then go on and program one of them. No problem is too small to make a program for.