Hell no, stopped using serial when I cant away my first external modem. My dad has a GPS, and that uses USB. It is a rather cheap one, too.
Some MoBo's come with them onboard, but not usually. They come with a little connector that fits in the card slot on your case and plugs into some pins on the MoBo.
The cable I have for my cell phone is USB, but the computer picks it up as PCI. It is such a ***** to get working. Has that prolific chip, does somethign with stuff.