I like terminal applications, though for flashcards/spaced repetition I personally think a GUI is more suitable. I often use non-text media in this (pictures, formatted math, formatted text). I like Anki's approach where the flashcards are HTML.
I agree, html works great for flashcards, and I make heavy use of images and audio
If you like Anki and GUIs you might also like Mochi [0]. It supports markdown, media, latex, etc. (and HTML if you really want to use it)
The `quiz` program in `bsdgames` is basically this.
Last few times I've looked into spaced repitition, there still didn't appear to be a decent wikipedia style repository of freely licenced, collaboratively produced flashcard sets. Seemed like a missed opportunity.