ADCH++ is a reference hub (server) implementation for the ADC (Advanced Direct Connect) network. It supports Windows / Unix platforms and is extensible with scripts in lua and python (so far) as well as C++ plugins.
VerliLinker is a Lua script written for Verlihub, that allows different hubs to be linked into a network (like IRC networks). The work is done using LuaSockets library in non-blocking mode. More at: http://forums.verlihub-project.org/viewforum.php?f=102
NextHub is a powerful file-sharing server written in C#. It implements the ADC protocol and will run under any platform supporting the .NET 2.0 framework. The emphasis on NextHub is performance, simplicity, and extendability.
A little different Direct Connect client for windows and linux, based on DC++ with script support(windows lua, linux sh and lua), segmented downloads, various spams and tricks