There's a better utility available than ncat. It's called socat. It has more features than ncat that people might find useful.

http://www.dest-unreach.org/socat/doc/socat.html#EXAMPLES

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.

Ncat is also more compassionate regarding command line parameters.

Depending on the nc app you have installed on your machine, params will have to be passed using different flags or in differing orders (someone should post why there are different kinds of netcat, I forget). Ncat accepts either format, and sends you cards on your birthday.

I second that Nmap recommendation.

Also, fping is an excellent ping sweeper if that's all you need (and it's now being updated again).

http://fping.org/