Is there any DAC that generates a negative voltage or sine wave without offset?
How about a DC blocking cap with a resistor to bias the output at ground (simple RC high pass filter)?  It's rather easy to shift signals around if you don't care about preserving the DC component.  

There are definitely lots of DACs available that support bipolar analog supplies, but they may be a bit expensive.  If you plan on performing any analog signal processing or buffering with op amps, then it may not be worth finding a DAC that can produce a bipolar output as you can just shift the DAC output in one of the amplifier stages.