Hi,
I was also after the same thing 'kenmac' was, using the USART in sync mode. Although my app relied on there being no gaps inbetween bytes, regardless of clock (wanted to stream bytes without framing bits). The USART is still useful in sync mode, using a shiftregister at the reciever, but there is a 'gap' between bytes that does not appear in the datasheet. So effectively it sends a byte, then waits one bit period, with the clock line idling high, then sends another...
With an inverter or two, I've used the USART as an SPI port (output only) and it does work well, if only I could find a way to stream bytes back to back at high speed.....I'll try some ATMEGA chips next.
But yes, I agree, the UART is more useful thatn the USART, althuogh they can both be used for async, the sync part seems to be redundant for most people.
Blueteeth