Endless possibilities. The owners manual came with schematics in case you wanted to wire it up to just about anything.

Compute magazine published software in the magazine, and you'd have to sit there for hours typing code into the console, but at the end you've have software that someone else designed.

If you had a modem you could dial a bbs and talk to people or trade games. Copying games and software was trival which allowed all sorts of things to flourish.

I even had a point and click mouse for mine and had purchased a module that would do speech to text, albeit very rudimentary.

Apple IIs were popular but largely limited to proprietary products. Commodore was built around the idea that the computer is just a processor for something larger.. whatever you wanted to build, and not limited to software.