If using index cards for memorizing, I think the Anki system can't be beat. Simple HTML/css formatting, tons of configuration options, plug in a .CSV with as many columns as you like and out the other end can come decks with cards configured in all sorts of wild ways.

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.