How to create USB on a Do It Yourself Arduino

I've been building do it yourself arduinos and all is well with what I've been putting together. Making PCBs and assembling the minimal components.

However... I'd like to dive into more complex stuff and add USB.

Anyone know of a tutorial on how to do this? I'd appreciate any push in the right direction. Thank you!

Look at the schematic for the Duemilanove - it uses the FTDI USB/serial chip which will give Arduino-compatible USB serial support.

There are other ways (other interface chips than the FTDI, and AVR processors with built-in USB support).

Thanks MarkT!