New from Shinywhitebox software (makers of the excellent iShowU screencasting software) comes Chatter, an iChat-helper application that does live screen demonstrations.
I am going to check this one out! My experience thus far with doing Leopard-based iChat screenscasts (better stated, Keynote sharing, etc.) have been medium-to-disappointing (too crunchy looking). The newer feature of ARD screen controlling, however, has been great.