Lugdunum
From AMule Project FAQ
Lugdunum is probably the most popular eD2k server.
It is currently available for Linux, Windows and several Unixes.
Lugdunum is free as-in-beer, but it's source code is closed.
Homepage: http://lugdunum2k.free.fr/kiten.html
NOTE: aMule is a separate project and is not related to Lugdunum in any way.