Additional Directories

I would like to utilise additional directories so I can have other "Open directory" directories.

This is so I can put different users into different non joined diectories so that names will not cross over etc via auto match in iCal etc....

What would be the best way to do this...?

Via a virtualised OSX server and then pull that directory into the main server...?

An open source "Open Directory " distro ?

any Idea's ?