GoBetwino is kind of a "genreric proxy" for Arduino. It's a program running on a PC (Windows only), that will act on behalf of Arduino and do some of the things that Arduino can't do on its own. So it works like a go between, hence the name.
GoBetwino is free, comes with a detailed user manual, and sample Arduino sketches to show how it can be used.
GoBetwino can be downloaded here: http://www.mikmo.dk/gobetwino.html. Check the blog for information about updates, user suggestionns, and bugs.
GoBetwino is listening on the serial port, for "commands coming from Arduino, and in response it will do something for Arduino and possibly return something to Arduino.
GoBetwino defines a set of command types that can be used as templates to create actual commands. Arduino can ask GoBetwino to execute these commands, and return something to Arduino.
So what can GoBetwino do? Using the defined command types you can create commands in GoBetwino that Arduino can ask GoBetwino to execute. These commands can:
With combinations of these commands you can do things like: