The one I liked was during Tons of Steel, when she sang: He's temperamental more a DICK than a machine. There were also sections during space where Joan was chanting.
Also of note is Joan's rap during Caution, while playing with Phil & Friends at Bonnaroo on 6/18/06. For those interested this video is easy to find online. This rap includes Joan meeting her man wearing a negligee, a cocktail in one hand, a joint in another. The story moves on from there.