If you use this on top of programs like bash, well ermm, you get what you deserve ;).
Here's an example of how I used websocketd to create a little dashboard for monitoring Linux CPU/memory/IO stats. It basically uses websocketd to stream the output of vmstat to a web-page that plots the numbers: https://github.com/joewalnes/web-vmstats
Other useful examples: tailing log files, executing long running job and monitoring output, or interactive querying of datasets that require a long running 'cursor'.
This is not for everyone or everything. Remember that like CGI, a process is forked for each connection so it's not the kind of thing if you want to handle a million concurrent connections on a single server.
However for dashboards, admin tools, quick mashups, visualizations, etc - it's a pretty handy tool.