I stumbled across this feature during my bachelor studies:

echo "Hello World" > /dev/tcp/127.0.0.1/5000
echo "Hello World" > /dev/udp/127.0.0.1/5000

You need to be root (obviously) and its supported in bash environment - but not on all systems. You can also cat on the ports and use dns adresses. Its neat to just get a byte out :).

And if you need something more sophisicated, be sure to use the good old netcat ("nc")