There are drivers available for NetBSD/amiga for the following Ethernet-cards:
The significant thing with ethernet is, that it uses a broadcast-medium, i.e. there can be several hosts attached to one cable. This can be done either using 10base2 (thinwire) cables and T-connectors if the card has a BNC connector, or by using twisted pair (TP) cables. When using TP, you have to use a hub (multiport-repeater) to which to connect every single host.