PtokaX (windows) http://ptokax.sourceforge.net/
y.a.b.b.a http://www.disconova.com/utu/acdchub/
openDcHub (linux) http://opendchub.sourceforge.net/
shastahHub (java) http://www.lwave.ca/DCHub/
SbSoftEA
ASH
I myself favor the PtokaX hub which is very fast (1200 users tested), has major rule implementation (slots'n'share) and a working, excellent script engine implemented.
I guess no one knows the language LUA-script
![Smile :)](./images/smilies/icon_smile.gif)
I'm currently writing scripts in lua and preliminary op-bots (my Dirtybot) should be out soon.