Free ISPs for Linux?

Rob Gibson asks: "I have heard stories of people using free ISPs under Linux to connect to the internet, and was hoping to do so myself. Many of them have slow connection speeds or bad support. Almost all have ad banners. The one that I love under Windows is Worldspy.net, which offers fast access and good coverage with no banner ads. However, I am digressing. I called Worldspy's tech support number, and they are not giving out any information as to how I could connect in Linux. Has anyone had success using Worldspy's access? Any free ISP using the MicroPortal technology? One thing that would be helpful in my attempts to figure this out is some software that would passively monitor the modem/COM port for incoming and outgoing data while in use with another program. Does anyone have suggestions for Linux or DOS/Win?"