I looked into it more deeply, and it seems like that might be the issue.  I believe the way Mac writes files is different-- it goes and writes the folder location, but doesn't immediately write the contents, so if it is stopped early, then the folders show up with no contents.  This has come up again this week-- see my next post.

Diigo looks interesting.  I'm working on a list for the PD wiki so that I can link interested teachers.  Also, I;m thinking that Moodle could possibly be a platform for this type of sharing?

Sorry for the late response-- you know how school and snow get.  :)