Adding to Gryfon's reply, other choices should include getting a fully fledged USB host board in your system. That way, you should have a vast selection of USB based Ethernet dongles for your Amiga.
Rapid Road is generally regarded as a good choice. That being said, since you do have a PCMCIA port I would personally first explore that option.
Like Gryfon said, you can either stick to Miami or, preferably, buy a copy of Roadshow. Unlike Miami, it is being maintained by AmigaOS developer Olaf "Olsen" Barthel. As you probably guess, Roadshow blends exceptionally well with the rest of the OS. It's
not that expensive, and I by getting a copy you support the Amiga community at large.
