Try a search on freshmeat, and failing that google

There have been several hacks that implement telnet over http, but they have large drawbacks. Primarily, you end up polling the server to get information back to the client, which makes for really bad interactive performance. If you are doing this on a restrictive network (maybe your company's http is proxied) then you will probably run into other barriers like too many requests, or transfer limits.

I've tried to do this in the past, and just ended up slipping a modem into a spare box to call my home box that was connected to a cable modem.

-jackdied