[nsxwolf]

If you plugged in the Mini Memory cartridge, it added a POKE command to TI BASIC.

There was a common cartridge, "Disk Manager 2", which gave you common DOS-like disk management utilities.

The lowercase font really was absurd. A few programs redefined them with much more pleasant fonts. The "Adventure" module for running the Scott Adams text adventures comes to mind.

[ams6110]

The Editor/Assembler program gave you a better font as well as 40 colummns instead of the normal 32.

[nsxwolf]

That text mode is a lot nicer, but you give up sprite support to use it.