magicjack has a free conference number, that you can set up your own conference rooms
305-848-8888
to create a new room dial 2 then a 3 digit room number
to join a current conference press 1 then the 3 digit room number
the good thing about this - you can call from google voice...
i just found it, and have not talked with anyone on it yet, so do not know if there are any other undocumented features available with this...
EDIT
should put a link to where i found this
http://www.freemagicconference.com/
