1. There was the Bronze scene in the beginning, when Faith was introduced -
2. The scene when Cordelia questioned if that was Faith's real hair colour when she was talking to Scott.
Erm.. I think that was it for Buffy

1. In Angel - we had the nearly shooting Angel with an arrow.
2. Elbow to the face, when Faith was in her apartment.
3. Cordy's reaction to Faith being in Angel's apartment after she has her breakdown.
4. And the season 4 " Cordy" scene that wasn't really Cordy

I think that's all the time they had them interact at all on Buffy/Angel Seeing as they were my two favourite characters, I wish they'd been able to interact more one on one.