Dropped into the comments to mention socat. I use it regularly to debug serial and multicast issues or to lash up network logging for random shell scripts. It's a very valuable addition to the toolbox IMO.
Edit: somehow my phone managed to post this comment three times. I've deleted the others
I really like socat, and use it pretty regularly for interfacing with unix sockets. Ncat, and socat have a divergent featureset though. Some combination of the two yields good results.
http://www.dest-unreach.org/socat/doc/socat.html#EXAMPLES