Lounge

Does the Lesson module in Moodle include some clever algorithm for when a flashcard is redisplayed, based on time since last viewing and whether it was correctly identified previously?

Nope, but we'll write it in if you can find the funds. In 'flashcard' mode, lesson just shows you a random sampling of questions, then re-displays ones you didn't get right the first time. Of course you can set it so the student can do it multiple times (and with the clustering code, each time can be somewhat different), and grade on a high score or an average to encourage multiple tries.

Lesson imports questions in a variety of formats, so lesson questions can be traded in text files, or you can trade backup/restore zips.