Again not strictly on-topic, but very geeky and therefore cool. The Turnkey Domain Controller is a Linux-based file and print server that can be used as a Primary Domain Controller for Windows hosts...without the need for a Windows Server, ideal for a small, mobile or temporary office.
The file server feature is based on Samba, and print server functionality uses the Common Unix Printing System (CUPS).
Windows hosts can be added to the domain in exactly the same way that they would be to a Microsoft Active Directory Domain, and when logging in users can optionally have a personal H drive mapped as well as an S drive for shared use:

All users can also print directly to PDF and have created documents saved to their H drive automatically.

Administration of the server is done using webmin via a web browser, and the Linux command interface can also be accessed via a browser without the need for Putty or a similar command line tool.

You can read more, and download a pre-configured virtual appliance, on the Turnkey Linux web site here - http://www.turnkeylinux.org/domain-controller

When optionally combined with an email solution such as Scalix (http://blog.brightpointuk.co.uk/scalix) and potentially a VPN solution such as OpenVPN (http://blog.brightpointuk.co.uk/openvpn), all of which support Windows and Outlook on the desktop, these tools could provide all the functionality a small network needs.