Gobetwino
I can't guarantee that every mail will receive an answer but I will try.

Gobetwino is not restricted to work with Arduino, the serial port can be configured so it can work with most devices that can send and receive strings over a serial line.

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:
  • Start any program on your PC, either directly or via an associated file type.
  • Start Excel, send data from Arduino directly into the Excel sheet, save the sheet and email it, without touching your PC.
  • Send e-mails to a POP3 mailbox and have Arduino react to the contents of the emails.
  • Log data directly to a CSV file on the PC, so the data can be used in spreadsheets or databases.
  • Download a file from the internet and have Arduino ask for a specific line of data from the file.

Gobetwino is kind of a "genreric proxy" for Arduino. It's a program running on a PC (Windows only - sorry), 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.
Check my blog for information about updates, user suggestionns, and bugs.

The current version is to be considered a beta version, it probably still has bugs in it, and no long time stability test has been performed yet.
If you have comments, questions or whatever, mail me at: