Tulip, easily.
Forget this, it's obsolete. When Intel bought DEC semiconductor rights they copied the design to make the 82559.
I remembered 2 links:
Realtek 8139 driver source for linux &
NE2000 card driver sourceThe most popular chipsets, in no particular order are, AMD, Intel, Realtek, National Semiconductor, 3COM & SMSC. In the UK I have come across the Intel, 3COM and Realtek parts the most.
Develop the Realtek 8139 and NE2000 drivers and you will satisfy most users, myself included.
If you want help/advice on ethernet drivers and IP stacks, contact me privately. I've ported Linux ethernet drivers, written them from scratch and wrote my own IP stack.