An interesting thing I chanced upon today, twIP is an IP Stack small enough to fit into a tweet :)
More from the author's website :
"twIP is a really, really tiny IP stack, written in 139 bytes of C code - small enough to fit in a Twitter message. Ok, so it is very far away from a real IP stack, but it can do the first task of an IP stack: respond to pings. The entire source code for version 1.1 can be found this tweet (139 characters long - version 1.0 in this tweet, 128 characters long). "
The page has instructions on making it work too.Great stuff!