Interesting post on a company called Netli and its product/service to speed up content delivery by creating a new protocol layer on top of IP (eg, creating Netli/IP instead of TCP/IP): Who Has Time For This?: The Wormhole Factory: Netli's wormhole is an Internet Protocol (IP) router that speaks both TCP and the Netli Protcol--a layer 4 replacement that transfers a web page in only ONE round trip. Realizing that the universe wasn't about to replace its routers, Netli deployed its own routers, co-located across the US, Europe[…] At the server side, a Netli router converts the session back to TCP so that the servers have no idea (anthropomorphologically speaking) that they're not connected directly to the browsers.

At IBM we used to do some bizarre stuff like tunneling SNA through TCP/IP and the reverse. Sometimes I wonder if IBM killed off APPC too early (APPC was a bear to set up, but once configured transferred data faster than TCP/IP over the same wire. I'm hazy on the history now, but if I recall correctly APPC let you set up a conversation and then initiate separate data transfers in that conversation, so more session-oriented than TCP/IP. Then again, using HTTP/1.1 pipelining one should be able to eliminate much of the setup lag when requesting a new URL from the same server).