I mentioned in this post that there was another blog that presented my need for some software that aids a teacher in managing user permissions. In the Macintosh world this is done, along with many other functions, using Workgroup Manager. There had been a product to do this, Sabayon, but it no longer worked with the current version of Edubuntu.
One of the people that responded to that post (there's 36 comments to that post at this point) was Andreas Olsson a systems administrator from Sweden. He proposed an idea similar to what Jordan Mantha had proposed, to put users in groups and then adjust the permissions for different applications so that only members of group x could use this program. Also, he proposed creating a small Command-Line Interface (CLI) program that could work off a database of the programs and groups and make this permissions-changing thing happen.
Well... He made this program :-) and it works GREAT. I've added 40 applications to the database using his program. As needed, I can roll back the permissions to the original ones.
These apps now belong to one of 4 groups: level1, level2, level3, or level4. I've put all students in the level1 group. After a week of successfully using the computers with that level of permissions, I'll add them to the level2 group, adding on these permission, also. And so on... They gain permissions as they demonstrate responsible computer behavior. If they do the porn image thing etc then they tumble back to level1 and must again work up to higher privileges again.
So... looks like all I've got left is customizing squid and running last bit of cables... the latter is trivial, the former, not. but... SOON!