WIZnet's range of Embedded Ethernet controller Chips, which inlcudes the following:

RTL8201CP-VD-LF is a single chip/single port PHYceiver with an MII (Media Independent interface)/SNI(Serial Network Interface) and implements all 10/100M Ethernet Physical-layer functions. A PECL interface is supported to connect with an external 100Base-FX fiber optic tranceiver
W3100A-LF is a fully hardwired TCP/IP stack supporting TCP, UDP, IP, ARP, ICMP, MAC internet protocols. Features include amazing protocol processing speed depending upon MCU); 8051 (max. 1Mbps), AVR (max.8 Mbps), ARM7 (max. 21Mbps)
W3150A+ is a fully hardwired TCP/IP stack with support for ADSL connection (with PPPoE) and TCP, UDP, IP, ARP, ICMP, IGMP, PPPoE, MAC protocols. Features include High Throughput speeds; 8051(max. 1Mbps), AVR (max. 8Mbps), ARM7 (max. 21Mbps) and 10/100 Base-T Ethernet (Auto detection) support
W5100 is a fully hardwired TCP/IP stack with support for TCP, UDP, ICMP, IPv4 ARP, IGMP, PPPoE protocols. Features include 10BaseT/100BaseTX Ethernet MAC/PHY embedded support and ADSL connection (with PPPoE Protocol with PAP/CHAP Authentication mode)
W5300 is designed for Internet embedded applications. The full hardware logic integrates 10/100 Ethernet controller, MAC, and TCP/IP with communication protocols such as TCP, UDP, IPv4, ICMP, IGMP, ARP and PPPoE. The data communication memory is extended to 128Kbyte and supports 16-bit bus interface.