Outside of the the JW call: "Alright, how do you like that Irish rock!?", I'd say the best moment came from the caller from Minneapolis' "Prince Tidbits", which should become the name of a Newbridge character.
The worst was the Graham Parker caller, just an AV club comment coming to life in the form of a Best Show caller. Also, 90% of the callers were dudes who all kinda sounded alike.