uIP-AVR was a port of Adam Dunkel's uIP - A Free Small TCP/IP Stack - to the Atmel AVR series of microcontrollers. It was a port of of uIP version 0.90, supporting communication over Ethernet using the Realtek RTL8019AS or Asix AX88796 NICs. uIP is now a part of the larger Contiki project, and my port is extremely out of date. Some of the code I wrote is now a part of Contiki.
In case it is still useful for someone the code is still available, though I would look at Contiki if I were starting a new uIP/Ethernet project on the AVR.
May 09, 2004 uIP-AVR 0.90.0 (port of uIP 0.90)