With NT Canuck, ObiWan created the Treewalk DNS program. These are some of ObiWan's 'faves':
Jana Server
Jana is a full featured proxy server, with browser-based administration, port mapping, mail services, access control and a whole lot of features. Coupling it with Privoxy and adding a firewall will allow you to connect an entire LAN to the Internet at no cost.
Mercury/32
The complete mail server, it supports POP3, SMTP and IMAP, mail collecting, SPAM filtering and more. Mercury can run on Win32 or Netware and has enterprise-wide load capabilities. It even supports user-written plugins and handles mailing lists.
Xitami
Xitami has tons of features, really low system overhead and resource requirements, and is the best for low-powered systems or to quickly setup a web site or to play along with a web server. It has browser-based administration for easy setup and configuration, plugin support and more...
WarFTP
This is one of the most popular FTP servers. WarFTP has lots of features, such as a good admin GUI which even supports remote server administration. The server is capable of HUGE traffic support and is in use by many Internet sites.
Privoxy
A fantastic filtering proxy! Privoxy allows you to define your own filtering rules using a powerful pattern matching language, can be chained with other proxies (such as Jana) or used alone to filter traffic for an entire LAN. It's one of the best popup/ad filters I've ever seen (and comes with full source code !!)
FileZilla
A nice FTP client (open source) with lots of features; file queue, timed downloads, parallel operations, SSL support and much, much more...
