ages ago I found oddbots cool h-bridge on this page which works quite well. I started with 100x160mm boards and made two boards for two bridges in order to controll 2x2 motors.
A few weeks ago I got into contact with the pcb-tool Eagle and gave it a try to place two h bridges on one board 100x80mm (freeware edition).
As far as I can see I just copied the bridges. The only think that differs from the two-board version is, that I used the same power/gnd traces for both bridges.