So for example I have a Japanese learning deck with columns "word - Japanese", "example sentence - kanji", "example sentence - hurigana helper text (phonetic speller for characters I don't know)", "English definition for word", "English definition for sentence", "part of speech" , "commonality of word.".
So I can make decks sorted by commonality of words with English on front, or Japanese on front, to practice vocabulary. Or I can have one with English sentences on front to practice sentence building.
You can even attach media files, like audio.
And best of all, last I checked this is all free. Still not sure how the creator funds hosting public decks.
I use it for languages, math, and code (there is a really good markdown plugin).
15-30 minutes every morning is enough to keep many things fresh in memory.
I actually find I am reading and learning more because I no longer worry about trying to remember things. I think of it as anki's job to remember, and my job to understand, so now I have more mental resources to spend on understanding material.
I'm rambling, and I apologize, but I HIGHLY recommend anki.
The main motivation was to have a structured note-taking tool always at hand so I'd actually use it. For that reason, all the commands are as low-friction as I could make them: the program itself is called 'zk', and all the commonly-used commands are abbreviated to one character, so instead of "zk new" to make a new note, I say "zk n".
It's something I'm still playing with and tweaking, but I went ahead and pushed my latest changes to the repo at https://github.com/floren/zk so if anyone besides me finds it useful, so much the better. The README does an ok job of explaining usage, although it doesn't document the 'link' and 'unlink' commands yet because I'm not sure how much I like that concept. I apologize for the Go code being a little clunky and redundant in places, because I've been growing it organically.
Index cards are incredibly flexible. Anybody who has made it through elementary school can use simple office supplies to construct rich, elaborate systems to support particular workflows.
For software to come as close in utility requires a trained professional to put in a fair bit of labor, and that is done in large part by closing off possibility. Trello, a very good product, has tried to stay a pretty generic card-like tool. But it's mediocre for kanban workflows, and downright terrible for a flashcard deck or a recipe collection or quickly jotting a shopping list that you hand to your partner.
As an aside, getting words on the card faster is often a negative. As others mention, hand-writing something aids memory. It also makes me choose my words more carefully, and write less. I find writing less to be especially valuable during software planning, in that I see cards as tokens for conversation. The more people can write, the more they try to turn them into mini-specs, which shifts them away from collaboration and back toward waterfall-ish isolation.
That said, I still like to use actual index cards especially because they are slower. Writing text by hands gives time to think what needs to be done and how best to express it. And doodling is fun.
[0] https://takingnotenow.blogspot.co.za/2016/03/one-way-i-organ...
[1] http://ctan.uib.no/macros/latex/contrib/flashcards/flashcard...
I use a real notebook & index cards during the day, but digitise them into org-mode each morning as part of my slip-into-work-mode ritual. That way I always have my recent stuff physically to hand, but I also have everything electronically archived and searchable on my computer too.
If I could just get emacs working on my phone (and extend it to be pleasant to use with touch alone) then my life would be complete.