Hi,
We published a beta version of Bubrary, which is available at
http://www.bubrary.net. It roughly similar to Supermemo, i.e. it uses
flashcards and spaced repetitions, but we were not trying to clone or
mimic the original Supermemo. We try to open a possibility of
collaboration between users; therefore all learning material hosted
there is free: i.e. "free" like in "freedom" - you can do almost
anything with it, and "free" like in "free beer" - no charges for the
learning material.
In Bubrary, most of us have had a lot of experience with Supermemo,
for example, English is not my native language - guess how I was
learning it.
If you want to set up a user, the anti-spam invitation text for now is
"titan". We are very curious what you think.
Happy learning,
Piotr (on behalf of Bubrary)