UDP is a Message protocol (same layer as TCP) used for broadcast or connection without reliability.

For TCP/IP stack, check www.scenix.com
This is a small 8-bit microcontroller (PIC compatible) but run at 50MHz.
In 2K of code and 136byte of RAM, they implemented UDP/IP/ICMP/PPP layer ...
Great ....

And in a lightly bigger version of the controller (4k of rom and some byte more as ram), they have implemented HTTP/TCP/IP/PPP layer to made Embedded web site (The site is contained in a EEPRom (HTTP page, PDF file to download, Java applet)... and the code (in assembler) is free with some interresting DOC about TCP....

I'm currently working on embedded web site with a 80C320 or a 16-Bit Fujitsu controller (90F543).

Maybe more info in the future ...