This is a short guide on how to make the slug an ethernet bridge. This can be useful if you have added an usb ethernet adapter, however there are other reasons why you might want to do this:
The advantage of bridging is, that you don't need any routing, so it is simpler to setup in small networks.
The only extra problem with briding on the slug (if compared to other linux boxes) is, that you're normally connected via SSH (unless you have serial - then forget about my guide ;) ), so in the moment you add eth0 to the bridge, it becomes unavailable and the ssh connection gets close, so you can't finish up your bridge. But one step after another.
Note: 192.168.XXX.XXX is the address which was assigned to eth0 before / your gateway address, netmask should be adjusted to your needs.
Now run the script. (I used nohup [scriptname] to run it, but as the ssh connection stayed alive, i think this should not be necessary.) Check if the bridge is created properly:
TK: followed this on openslug using a dhcp server. After running script unable to access slug, "no route to host"