Hi Fox,
here are some more:
Analog devices:
AD8400/8402/8403
or
Xicor:
X9C104
I am using the AD 8403 in an application.
It has four potentiometers and it is controlled with an SPI-3-wire
Interface. the potentiometer has 256 positions.
the X9C104 has an UP/DOWN interface and 100 positions.

Best regards
Christian