NMenu is an old NetWare utility to create application menus for users. It does incorporate such things as the user ID and group memberships to determine which menus to display.
However, it is ultimately a DOS menu utility, not unlike Direct Access. I would suggest not bothering with NMenu in a Linux-server environment because all the elements which make it very useful to NetWare admins won't be available in Linux. Plus, I don't think that there's any way to get Linux to run NetWare-style login scripts, which is how NMenu is usually loaded.
You'll definitely need to take a workstation-oriented approach to this. ady2k's suggestion is good, regardless of the menu system used.