Read and store data with the usb
I don't have experience with Processing, but probably that is what you need. It communicates through USB and with the CreateWriter function, you can create a text file.

More about Processing can be found at Processing

Also another thread at Electronics stack exchange might help:

Related question

Alternatives (also mentioned in the above thread):


Use serial port directly with a terminal application on the PC
Use an SD card inside the Arduino to log