Ran across this today, looking for alternate ethernet chips for my
furnace (boy, that doesn't get old... ethernet furnace... ethernet
furnace... ;)
http://www.silabs.com/tgwWebApp/public/web_content/products/Microcontrollers/Interface/en/CP220x.htm
This is a 48-TQFP (0.5mm pitch) chip with an 8 addr 8 data standard
"parallel" MPU interface on one side, and a simple twisted pair
interface (i.e. direct to an rj45 with integrated magnetics and LEDs)
on the other side.
There's a 28-QFN version with multiplexed bus if you need it to be
about 0.5cm square ;-)
The only drawbacks are that it's a 3.3v part (no 5v option), and
requires a 1:2.5 Tx transformer (less common than the 1:1).