In December 2004 DD-WRT was founded by Sebastian Gottschall with the initial target that was just a modification of the original Linksys Firmware for supporting simple Radius Authentication. Gottschall then decided to add some more small tools and fancy things, just for fun. Out from the great response from the DD-WRT Community, after releasing it to the public, Gottschall developed more features and started also to redesign the complete firmware.
The Firmware features:

Virtual SSIDs
Virtual DHCP-Servers
PPTP over WAN
Bridging + VLAN support
VDSL Support
OpenVPN
IPv6 Support
and Many More…

Untangle has created one of the most impressive applications of this principle. The Untangle Gateway bundles together a list of applications that even seasoned sysadmins couldn’t install and effectively manage in a timely manner.
As the official name indicates, The Open Source Network Gateway, is open source. As with most commercial open source offerings, you must buy the Professional Package to get some features, but surprisingly few. All of the core functionality is included in the OSS version; enterprise management goodies augment the product for the Professional Package offering. – Charlie …