Would be cool to allow people to assign a hot-key to a selection of barks, so they could create a soundboard of barks.
Other simple things would be "visualize this bark" where you have an audio waveform display of the bark (this has got to be easy to do programmatically) and possibly also a mechanism to categorize the barks by pitch or note. Then a user could find a dog with a deeper (or yippier) bark.