socat version; no loop, as it forks a separate process for each connection:

    socat TCP-LISTEN:8080,fork,crnl SYSTEM:'printf \"HTTP/1.1 200 OK\\n\\n\"\; cat test.html'

The extra quoting you need to do the the SYSTEM argument makes this rather cumbersome. socat is a powerful tool, but can sometimes be a pain to use.

Here's one use I found for it recently, when I wanted to do some experimentation with multicast:

    socat - UDP-DATAGRAM:239.255.1.1:4242,ip-add-membership=239.255.1.1:10.0.0.10,ip-multicast-loop=0,bind=:4242

This causes socat to bind to the multicast group 239.255.1.1 on the interface that has the unicast IP 10.0.0.10, sending and receiving on port 4242 over UDP, reading from stdin and writing to stdout. It basically gives you a simple chat service over the local network.