Richard Visokey of AD7C made a DDS VFO using AD9850 and an Arduino Uno:
I built a simple VFO for a direct conversion receiver I am putting together. The VFO uses an AD9850 DDS chip to synthesis a nice 1Vp-p sinusoidal wave. I used an Arduino Uno to set the AD9850 frequency, drive an LCD display, and take input from a rotary encoder to set the output frequency.
Project info at AD7C.
Check out the video after the break.