Programming and controlling microcontrollers and FPGA using Laptop (USB port)
If you look for a solution to interface your embedded controller to a computer with only USB ports, I can highly recommend an USB to RS232 bridge chip. I use the FT232 chip from FTDI in my embedded systems. FTDI not only provide the chip but also a driver for it. In your computer the chip will be detected as a good old COM port, just as the old ones with all the handshaking etc... In the controller end the chip outputs TTL RS232, SPI or I2C depending on your choice of chip.

If you are looking for parallel access, FTDI also have a USB to parallel chip.

The driver can be customized if you want too and is free. It works on Windows, MAC, Linux and Windows CE.

Now, if you only want to have a traditional 9-Pin COM port, there are several USB to RS232 converters out there.