well there is the simplistic expresspcb software but for something decent and free your only option is KiCad
I did play with both KiCad and the GEDA suite.
As I recall, I didn't find KiCad to have very good libraries of parts, in spite of all of the
user contributed stuff. It's been at least a year since I tried it, so things may be
different now. I do remember being unimpressed with the interface, enough that I didn't
feel compelled to switch from Eagle at the time.
The GEDA suite feels like a hodgepodge of programs just stuck together (and it is).
I've been pretty happy with diptrace because it seems that they have put some
thought into the user experience. Simple example between them and Eagle:
Suppose you draw a bus and connect up individual nets to the bus. In Eagle, you then
have to go select the naming tool, click on the net, and place the name of the net
on the line as it connects to the bus. Why? In diptrace, as you connect the net
to the bus, it is labelled automatically. If you use a lot of buses in your schematics, that
simple thing saves a huge amount of drawing time.
Scott