Blender.org

I don't know how difficult is implementing undo,
Some easy incremental-svaving and loading buttons simulating a real undo would be helpful
and easier to implement for the beginning.

1) as already mentioned, support for different standart (or less standart) formats would be nice. 2) I think, that a new format containing all (or maybe a selected subset) of informations that blender has about the model would be useful. Why not an xml-based format ? This should be easily parseable ...