Log4c:
http://sourceforge.net/projects/log4c/?source=directory
http://log4c.sourceforge.net/

log4cpp:
http://log4cpp.sourceforge.net/
http://sourceforge.net/projects/log4cpp/

log4cplus:
http://sourceforge.net/projects/log4cplus/?source=directory
http://sourceforge.net/p/log4cplus/wiki/Home/

log4cxx: