DDS chip capable of producing arbitrary wavforms

[jta]

I'm interested in incorporating a DDS (Direct Digital Synthesis) chip in a design, such as the ones at:

Direct Digital Synthesis (DDS) | RF/IF Components | Analog Devices

The design would benefit from the ability to produce an arbitrary waveform in addition to, but not concurrent to, a sinusoidal output.

I have heard that DDS chips exist that have on board memory which can be programmed with arbitrary waveforms, but have not been able to find one myself.

Any suggestions?

Thanks for your time.