I don't want to interrupt Rejetto's activities with what I will say now, but If you really need to create user groups maybe you can look for WWW File Share Pro http://www.wfshome.com.
Don't shoot me Rejetto, I like HFS very much 
Personally I think the system of passwords in HFS like it is at the moment is satisfying enough, after all HFS is more intended for small home use.
Greetings.
that's not really what i wanted to get,... sorry
To explain again:
- I'm working with diffrent filetypes in a Network with other ppl. All of them have diffrent accesslevels. So, not everybody can access the files his neighbour does. Some only need *.txt *.rtf, others need additional *.cpp and so on. Files are stored on a central station.
- What I need.
Filter to add only specific files to a folder, which is auto. updated.
Ability to do more than one password for a folder to access it.
(Client1 has access to folder1, Client2 has access to folder1&2, public client has no access)
For a later stage (optional)
- passwordprotected upload to server
